The product feed is one of the most important and most underrated parts of Google Ads for eCommerce. If the feed is dirty, incomplete or lacking any strategy, Shopping and Performance Max are working with weak data. And when the algorithm gets weak data, it can spend budget on the wrong products, the wrong queries or listings that simply aren't competitive.
Plenty of business owners look at the campaign, the ROAS, the budget or the conversions. Very few genuinely look at the feed. But for an eCommerce store the feed is the bridge between catalogue, Merchant Center, Shopping, Performance Max and commercial results.
A badly built feed isn't just a technical problem. It's a sales problem.
Why the feed decides how well Google can work
Google Merchant Center receives product data: title, description, price, availability, link, images, brand, identifiers, category, variants, promotions and additional attributes. That data is then used to show products in Shopping, Performance Max and other Google surfaces.
The official documentation on the product data specification is extremely detailed, because every attribute can affect approval, ad quality, matching with searches and competitiveness.
In practice: if the catalogue speaks badly, the campaigns speak badly too.
Mistake 1: product titles written for the ERP, not for Google
The title is one of the most important elements in the feed. Too often, though, it is pulled straight from the ERP: internal codes, abbreviations, unclear formats, missing brands, inverted words or decisive information buried at the end.
A product title should help both Google and the user understand immediately what you are selling.
Weak example:
Adult 12kg chicken
Better example:
Prolife Adult Chicken 12 kg dry food for adult dogs
This isn't about stuffing the title with random keywords. It's about including the information that matters: brand, product, variant, size, category, use or need.
Mistake 2: generic or badly copied descriptions
The description isn't there for poetry. It's there to clarify features, intended use, material, compatibility, format and real benefits. If it is too generic, incomplete or identical across dozens of products, the feed loses quality.
In our work on custom eCommerce platforms we also use AI plus human review to improve product pages, summaries, FAQs and product data. We covered this in the article on AI-generated eCommerce filters: the catalogue isn't just a product list, it's a commercial database.
Mistake 3: missing or wrong GTINs
Product identifiers such as GTIN, brand and MPN help Google recognise precisely what you are selling. If they are missing when they should be there, or they are wrong, you can lose quality, comparability and approval.
A GTIN must never be invented, duplicated or copied from similar products. It has to be the correct one. In sectors where products are standardised, this check is essential.
Mistake 4: inconsistent brands
The brand has to be consistent across site, feed, product page and categories. If in one place you write "Royal Canin", in another "RoyalCanin" and somewhere else "ROYAL CANIN UK", you are creating noise.
Brand consistency also matters for building strong brand pages, segmenting campaigns, using custom labels and understanding which brands are genuinely generating margin.
Mistake 5: prices out of sync
Feed price and site price have to match. If the feed says 39.90 and the product page shows 42.90, Merchant Center can flag problems or disapprove products.
This often happens when:
- the feed is refreshed too rarely;
- sale prices aren't synchronised;
- the ERP changes the price but the site doesn't;
- different variants inherit the wrong prices;
- VAT, discounts or price lists are handled inconsistently.
A serious eCommerce operation needs reliable synchronisation between catalogue, site and Merchant Center.
Mistake 6: wrong availability
Advertising products that aren't in stock wastes both budget and trust. If the feed says "in stock" but the site shows sold out, you are sending traffic to a page that cannot convert.
The opposite is just as damaging: products that are available but marked as unavailable in the feed stay out of the campaigns exactly when they could be selling.
Availability, refresh times and out-of-stock handling have to be designed. Not left to chance.
Mistake 7: weak, missing or uncompetitive images
In Shopping the image is often the first thing the user sees. If it is small, pixelated, with a cluttered background, a watermark, promotional text or a barely legible product, you start at a disadvantage.
Images must be consistent, clean, large enough and representative of the correct variant. A feed with the wrong images can attract clicks from uninterested users or push the CTR down.
Mistake 8: Google product category missing or too generic
The Google category doesn't replace your own site category. It exists so Google can classify the product more accurately within its own taxonomy.
Leaving categories too generic reduces precision and control. In large catalogues, the category has to be managed with rules, not set by hand product by product until the first mistake.
Mistake 9: badly managed variants
Sizes, colours, flavours, formats and pack sizes have to be handled clearly. If variants are confused, Google can show the wrong product, image or price.
The typical errors are:
- every variant sharing the same title;
- an image that doesn't match the variant;
- the parent product's price instead of the real variant price;
- size or format missing from the title;
- duplicate identifiers across different variants;
- a product URL that isn't variant-specific when it needs to be.
A wrong variant may look like a detail, but in Shopping it becomes a wasted click.
Mistake 10: unstable product links
The product link in the feed has to lead to a page that works, is fast, consistent and stable. If it keeps changing, redirects, returns a 404 or shows different content, you are making life harder for Merchant Center and for the campaigns.
This is even more delicate during a migration. In the checklist for changing eCommerce platform without losing Google traffic we insisted on redirects and stable URLs precisely because SEO, feed and Ads constantly overlap.
Mistake 11: disapproved products ignored for weeks
Merchant Center flags products that are disapproved, limited or carrying warnings. The problem is that many accounts just leave them there. Meanwhile part of the catalogue isn't entering auctions at all, or is entering them badly.
A feed review should always include:
- disapproved products;
- products with warnings;
- price and availability issues;
- image issues;
- identifier issues;
- products excluded from destinations;
- the error history after catalogue updates.
Mistake 12: custom labels not used
Custom labels are among the most useful tools for segmenting Shopping and Performance Max campaigns. And yet many feeds don't use them at all.
With custom labels you can distinguish products by:
- high, medium or low margin;
- best sellers;
- seasonality;
- stock to clear;
- new arrivals;
- priority brands;
- price band;
- products with plenty of stock;
- products with frequent returns;
- loss leaders you don't want to push too hard.
Without custom labels you usually end up treating the whole catalogue the same way. But not every product deserves the same budget.
Mistake 13: the same feed for every objective
A feed shouldn't just be "all products uploaded". It can and should support the strategy.
If you want to push margin, you need to be able to identify the high-margin products. If you want to clear stock, you need to be able to identify it. If you want to protect best sellers, you need to know which they are. If you want to avoid products that generate a lot of returns, you need to be able to exclude them or treat them differently.
The feed has to talk to the business, not just to Merchant Center.
Mistake 14: slow synchronisation with ERP and stock
A feed refreshed once a day may be enough for some catalogues and nowhere near enough for others. If prices, availability or promotions change frequently, you need more precise synchronisation.
This is one of the reasons a custom eCommerce platform can make a difference: catalogue, ERP, stock, feed, prices and campaigns can be connected in a more controlled way than with a stack of plugins.
This is something we work on directly in bespoke eCommerce development, because the feed isn't an accessory: it's part of the commercial infrastructure.
Mistake 15: nobody checks the feed after launch
A feed isn't something you fix once and then forget. Every new product, promotion, price change, new variant, new brand or migration can introduce errors.
You need a periodic review of:
- approved and disapproved products;
- recurring errors;
- title and image quality;
- price and availability consistency;
- up-to-date custom labels;
- products that get clicks but few sales;
- products that spend without margin;
- categories or brands poorly covered by the feed.
An unmonitored feed is a slow loss: it doesn't always blow up, but it burns budget every single day.
How to tell whether your feed is wasting budget
There are some very practical signals:
- lots of disapproved or flagged products in Merchant Center;
- PMax spending on low-margin products;
- best sellers getting no impressions;
- out-of-stock products still receiving traffic;
- product titles that are hard to read in Shopping previews;
- images that differ from the product clicked;
- decent average ROAS but terrible ROAS in some categories;
- no segmentation by margin or seasonality;
- feed prices that differ from site prices;
- an agency that only ever talks about campaigns, never about the feed.
What to ask your agency
If you use Shopping or Performance Max, these questions are non-negotiable:
- How many products are disapproved or limited? I want the number and the reason.
- When is the feed refreshed? Prices and availability have to be reliable.
- Are titles optimised for search and Shopping? Or do they come straight from the ERP?
- Are GTIN, brand and MPN correct? Identifiers are not to be invented.
- Do the images meet the policies and are they competitive? It isn't enough that they exist.
- Are we using custom labels? If not, how are we segmenting margin, seasonality and priority?
- Which products are spending the most budget? And which are generating margin?
- Is the feed connected to the ERP? Or is it updated through fragile processes?
- Are the variants correct? Price, image, format and availability all have to line up.
- Is the feed reviewed every month? Merchant Center isn't a panel you open only when something breaks.
How we handle it at BitHub
When we work on Google Ads for eCommerce, the feed isn't treated as a technical file to upload and forget. We read it as part of the strategy.
We check titles, images, prices, availability, GTINs, variants, custom labels, categories, excluded products, synchronisations and consistency with real objectives: orders, ROAS, margin and traffic quality.
This connects directly to Performance Max: if PMax receives a weak feed and the wrong conversions, it can learn badly. We covered this in the article on Performance Max for eCommerce and cart vs order conversions.
In our approach, site, feed and campaigns are not three separate worlds. They are the same commercial system.
Frequently asked questions
What is the Google Merchant Center feed?
It is the set of product data sent to Google: title, description, price, availability, images, link, brand, identifiers, category and other attributes useful for Shopping and Performance Max.
Why does the feed matter for Performance Max?
Because Performance Max uses product data to serve ads and find opportunities. If titles, images, prices or availability are wrong, the campaign is working on weak data.
What are the most serious feed errors?
Prices out of sync, wrong availability, missing or incorrect GTINs, weak images, disapproved products, confused variants and no custom labels to segment the catalogue.
Are custom labels mandatory?
No, but they are very useful. They let you segment the catalogue by margin, seasonality, best sellers, price band, stock to clear or commercial priorities.
How often should the feed be updated?
It depends on the catalogue. If prices and availability change frequently, you need a very frequent refresh. What matters is that Merchant Center and the site show consistent data.
Can a disapproved product lose you budget?
It doesn't spend directly if it isn't shown, but it can reduce coverage, break the strategy and leave important products out. Feed errors should be fixed, not ignored.
Can the feed affect ROAS?
Yes. If the feed pushes low-margin products, out-of-stock products, weak titles or uncompetitive images, ROAS can get worse even with a campaign that looks well configured.
Do you need a developer to fix the feed?
Often yes, especially when the problem starts in the ERP, the synchronisation, the variants, prices, availability or catalogue logic. Not everything can be solved from the Ads panel.
Want to know whether your Merchant Center feed is helping or holding back your campaigns? We can review the feed, Merchant Center, Performance Max, Shopping, custom labels and consistency with your real catalogue.
Get in touch for a feed and eCommerce Google Ads audit.
Useful sources: Google's official specification for Merchant Center product data, the custom label attribute, the GTIN attribute, the price attribute and the availability attribute.