Three Shopping Campaigns, One Overlapping Product Set
A single Merchant Center feed supplies three standard Shopping campaigns in the same country and currency: 'Brand-Exact' (priority High, manual CPC max $0.40, $90/day), 'All Products' (priority Medium, tROAS 500%, $1,400/day) and 'Clearance' (priority Low, manual CPC max $0.55, $350/day). All three contain the same 380 clearance SKUs, because nobody excluded them when the clearance campaign launched. Last 30 days: Brand-Exact spent $2,600 at ROAS 540%; All Products spent $41,000 at ROAS 460%; Clearance spent $9,800 at ROAS 610% but received only 3% of its eligible impressions. Twelve clearance SKUs account for 60% of Clearance spend, and those same twelve show a 34% higher cost per conversion inside All Products. There are no shared negative keyword lists and no campaign-level product exclusions in place.
1. Explain why the Clearance campaign cannot win impressions for the 380 overlapping SKUs despite its higher max CPC, and state what the auction actually compares.
Read the worked answer
Priority is a tie-breaker inside your account, not a bid. When the same product is eligible in more than one standard Shopping campaign, Google selects the campaign with the highest priority that has a product group covering that product with an eligible bid. Only that campaign's bid enters the ad auction. Lower-priority campaigns are not given a second chance and do not compete against the higher-priority campaign.
Here, All Products (Medium) covers all 380 SKUs, so it always pre-empts Clearance (Low). Clearance's $0.55 max CPC never reaches the auction, which is exactly why it holds 3% of eligible impressions - it only serves SKUs that All Products happens not to cover, if any.
What the auction compares is your ad rank against other advertisers: bid, quality signals, expected CTR, landing page and the formats eligible. Your internal campaign priority is resolved before that, so raising Clearance's bid is a no-op.
The 34% higher CPA for those twelve SKUs inside All Products is the symptom: a tROAS 500% campaign is bidding them to its own target, not to the clearance economics, so they underperform there while being blocked from the campaign built for them.
2. Recommend a restructure that preserves the clearance bid advantage without splitting the feed, and state the reporting consequence.
Read the worked answer
Restructure
- Give Clearance a product group that is the only coverage for those 380 SKUs: in Brand-Exact and All Products, subdivide by
custom_labelor item ID and exclude the 380 (set the product group to 'Excluded' rather than removing the bid). Then each SKU is covered by exactly one campaign and priority stops mattering. - Alternative if exclusions are impractical: raise Clearance to High priority and confirm it does not overlap Brand-Exact. But that just moves the collision, so the exclusion is the durable fix.
- Verify with the 'Products' view in each campaign that no SKU has coverage in two campaigns.
Reporting consequence
Spend and conversions for those 380 SKUs jump from All Products to Clearance. All Products' ROAS will appear to improve while its volume drops; Clearance's ROAS will fall from 610% because it now absorbs budget it never had. Neither change is performance. Re-baseline both campaigns from the switch date, and compare the 380 SKUs as a cohort across the transition rather than comparing campaign-level ROAS before and after. Expect the blended result to be the honest number: the twelve SKUs should land closer to clearance CPA, which is the point.