ACoS jumped from 33% to 55%. Nothing had changed in the campaigns

A specialist's job is not only to supervise how the ads perform. It is to watch the listing they point at.

Here is why.

What happened

Advertising was working and profitable. Then, over several days, the metrics started deteriorating, with no changes made to the campaigns.

We checked the obvious explanations first. The niche was in the middle of its high season, so seasonality could not account for it. Recent changes in the campaign manager showed nothing that would explain the decline.

ACoS rose from 33% to 55% while conversion rate fell.

The one parameter that had changed

The rating had dropped by 0.2 points.

Analysing the listing, we found a new negative review. We contacted the buyer immediately and were fortunate enough to agree that it would be removed.

Why this matters beyond one account

A fifth of a star does not sound like an event. In a competitive niche, at the moment a shopper is comparing two near-identical options, it is enough to move conversion. Conversion is the number every advertising metric is built on.

Nothing in the ad account would ever have shown this. Someone had to look at the listing.

A product manager often catches issues like this. Sometimes they do not, which is why the advertising specialist should be looking too. The ad account tells you performance changed. It does not tell you why.

The ASIN inspector is where we start on a question like this. It puts the rating, the price and the sales rank on one timeline, so a change in the listing lines up against the week the ACoS moved.