Why it matters
ROAS makes ad accounts comparable and keeps spend accountable, but revenue isn't profit, and platform-reported ROAS credits ads for sales that often would've happened anyway (brand searches especially). Chasing reported ROAS without those caveats grows the metric, not the business.
How it works
Revenue attributed to a campaign divided by its spend, with all the fragility attribution brings. A sturdier companion: know your break-even ROAS from margins (low-margin products need far higher returns), and sanity-check platform claims against actual revenue movement.
What to do about it
Set target ROAS from your margins, not from platform benchmarks. And run the occasional holdout test: pause a "high-ROAS" branded campaign for two weeks and watch whether revenue drops.
