The best marketing agency for a large catalog is the one that has already fixed your hardest data and measurement problem at a scale like yours, and platform badges, logos and awards only matter once that fit is established.
This guide is published by SCUBE, and SCUBE appears in it. It doesn't rank agencies. It explains what common agency credentials measure, which kind of agency suits which constraint, what an agency should already know about your catalog, and how to vet a shortlist before you sign.
At a few hundred SKUs, choosing an agency is mostly about creative quality and price. Past a few thousand, the catalog becomes the account, and the agency's real job is deciding which parts of it deserve spend. Several things change at once:
Here’s what often happens: spend scales faster than understanding, efficiency holds just long enough to hide the problem, and by the time margin thins, the structure that caused it is two quarters old. Growth doesn't stop. It caps, and nothing in the dashboard says why.
That is why the useful question isn't which agency is biggest or best known. It's which agency has already fixed your hardest data and measurement problem at a catalog like yours.
The scorecard below is SCUBE's suggested starting point. It is not an industry standard, so weight it to your own catalog and margins.
Any one of these is a reason to slow down. Two is usually a reason to keep looking.
Most marketing agency credentials measure something real. It just isn't the thing a high-SKU brand is hiring for.
Google's Partner badge is the clearest example. Per Google Ads Help, an agency qualifies with a 70% optimization score on its manager account, $10,000 in ad spend across managed accounts over 90 days, and at least half of its account strategists certified. The agency can apply or dismiss the recommendations behind that score. Premier Partner status goes to the top 3% of participating companies in a country, ranked on client growth, client retention, share of non-Search spend, and annual ad spend.
That tells you an agency runs real budgets and keeps its team trained. None of the requirements measure profit, margin, or how well an agency handles a catalog with 100,000 SKUs. An agency can hold the badge and still run your whole feed as one undifferentiated block.
The other common signals work the same way:
Use these as one input. Then confirm any agency's current status in the platform's own partner directory, including SCUBE's, rather than relying on a badge on a website or a line in a roundup.
Marketing agencies are usually sorted by channel: paid, SEO, social, creative. For a large ecommerce catalog the more useful sort is by constraint, because the constraint decides which kind of partner you need.
Many brands need more than one of these partners over time. Write down which team owns the product feed, which owns tracking, and which owns the reporting finance will trust, because those three decisions touch every channel. When they sit with different teams, each team optimizes its own number and nobody owns the margin.
Spec-driven catalogs fail in specific, repeatable ways, and an agency that has worked in your category can describe them before it opens your account. These are the tests worth running in the first call. Auto parts is the example because fitment makes the problems easy to see, but the same logic applies to any catalog where compatibility drives the purchase.
ACES/PIES is a foundation
Standardized data is clean and rich per SKU, but every competitor on the same feed starts from the same base. The data still has to be extracted, broken into usable attributes, and rebuilt into pages, categories, and filters that shoppers and search engines can use. An agency that treats "we have ACES/PIES" as the win has left you competing on price and shipping speed.
Fitment isn't one thing
Ask how many fitment patterns the agency sees in a catalog like yours. A good answer names at least five:
Treating all of it as year/make/model is wrong for a meaningful share of any real catalog.
Buyers aren't one group
OEM versus aftermarket is one split. Replacement versus upgrade is another, with different urgency and different messaging, and tire buyers don't behave like wheel or brake buyers.
Structure sets how specific a search result can get
URL and category structure decide how closely a page can match what someone typed, and a wrong choice is expensive to unwind at scale. The agency should be able to say which structure you run and what it costs you before it recommends changing anything.
Product and category pages have different jobs
A product page needs a title, meta description, spec section, FAQs, and proof such as reviews. A category page needs enough unique content that it doesn't read as thin or duplicate when hundreds of them look alike. Any agency using AI for this work should name verification against your catalog data as its own step, because an invented spec or compatibility claim means a return and a wrong part on someone's vehicle.
Wrong-page clicks need a way back
Some clicks will land on the wrong part or the wrong vehicle. Ask what happens next: whether the shopper can edit the vehicle and continue, or hits the back button. That is a separate fix from ranking well.
Visibility no longer ends at the click
An LLM recommending a product without a visit is now an acquisition channel with its own mechanics, and accurate structured fitment data is what lets it recommend the right part. The traffic that does arrive still has to confirm the product match, build trust, and prompt action.
Content starts with the use case
"What do I need to run 37s on my Jeep" cascades into a lift kit, tires, wheels, and accessories. "What is a tire" doesn't.
An agency that can't answer these before it sees your account will learn them on your budget. Wasting not only your money but also time getting up to speed on your store’s specific needs.
Since SCUBE publishes this guide, here is where it sits on that map, stated as plainly as we can.
SCUBE works with ecommerce brands that sell functional, spec-driven products with large, high-SKU catalogs: auto parts, industrial and manufacturing, construction supplies, heavy equipment & parts, electrical components, marine & boating parts. The work starts with diagnosis. The SCUBE Game Plan is a free review of tracking, product data, and account structure, including how spend splits between branded and non-brand demand and how the media mix lines up with gross profit targets, not only ROAS. It ends in a 90-day roadmap.
The approach is feed-first. The product feed, the campaign structure, and the reporting are treated as one system, because a change in any of them moves the other two.
Here is what that looked like when rebuilding paid ads for specialty auto parts retailer with more than 100,000 SKUs. Paid spend was moving and revenue had plateaued, but profit after advertising was inconsistent and platform reporting didn't match how demand was being captured. Branded and non-brand demand were separated. The feed was rebuilt around performance tiers, with MPNs and brand names added to titles and low-yield products pulled from paid paths. Google Ads became the primary demand layer, Performance Max was structured so it couldn't blur reporting, and Microsoft Ads was added for incremental demand. ROAS stayed in the account as a constraint, not as the definition of success. Over the next 12 months, profit after advertising costs rose by $530,000 year over year and revenue grew 22%. The gain came gradually, as spend stopped feeding low-value demand.
SCUBE is likely a good fit if:
The limits matter just as much. SCUBE is not a brand and creative studio, and it is a poor fit for fashion, beauty, luxury home goods, or other brands where the purchase is driven by identity and storytelling. A small catalog won't benefit much from a feed-first approach either. If your main gap is creative or brand, seek out specialists for that work.
The process below is SCUBE's suggested approach. It is not an industry standard, so adapt the steps to your catalog.
Questions worth bringing to final interviews:
Pay attention to how specific the answers are. An agency that has done this work before answers with examples, numbers, and named owners.
The fee is only part of the bill. A realistic total cost includes:
Three pricing models cover most of the market, and each carries an incentive worth understanding:
The lowest fee is rarely the lowest cost. A structural problem left running, such as a feed sending spend to products that never return it, can cost more than the gap between two agency quotes. Compare proposals on what each one will fix first and how it will measure the result, then on price.
Is a Google Premier Partner badge proof of quality?
No. It shows an agency runs substantial budgets, keeps clients, and ranks in the top 3% of participating companies in its country on Google's measures. It doesn't show profit results or fit with a large, spec-driven catalog. Use it as one input, then judge the agency on references and a written plan.
How many agencies should I shortlist?
Three to five. That gives you a real comparison without turning evaluation into a second job.
What should a diagnostic produce before spend changes?
At minimum: findings on tracking, product data, and account structure; the split between branded and non-brand demand; how the current media mix lines up with gross profit targets; and a 90-day roadmap. The SCUBE Game Plan produces all of these.
How long before I see movement?
It depends on the channel. On the paid side, spend stabilizes first and growth becomes incremental afterward, which is slower than a bid change and steadier. For SEO for a large catalog ecommerce site, meaningful movement usually shows up within three to six months.
Should SEO and paid run through the same agency?
It helps. Paid search shows which queries and products convert fastest, and SEO can build durable organic visibility around those same patterns. When two teams own them separately, that feedback loop usually breaks.
If you want a read on where spend leaks and where demand is capped before you request proposals, book a free SCUBE Game Plan.
