ACoS was climbing on one product, so I optimized. Bids down on the expensive tar
By Elizabeth Greene · October 15, 2026 · Curated by George's Blog
ACoS was climbing on one product, so I optimized.
Bids down on the expensive targets, bids up where conversion looked decent, negatives added and structure tightened.
Then I did it again the next week, and again the week after that.
Three weeks of that, and pricing had shifted underneath me.
Same keywords and same shoppers in the same auction, and the click just wasn't worth as much anymore because the product next to mine was cheaper.
Ads sit inside everything else that's happening.
If sessions are down, if conversion rate slipped, if a competitor repriced, if a listing got weaker than the one sitting next to it, the ad account shows you all of that as a bad ACoS, which looks like a bids problem.
I should have asked whether spend went up while sales didn't follow, or sales dropped while spend held.
The bid only touches one of those.
Cutting bids leaves a conversion rate issue exactly where it was. I know that.
I've said it to people probably a hundred times.
I still catch myself reaching for the bid first, three weeks in, in my own account.