I started to rebut this with the expected value of the bid... but if you're advertising a sports car, it's worth paying $100/impression even if your conversion rate is 1%.

If the ad impression is worth that much (which seems extremely rare), then there's a profitable trade to be had, where I'm paid to see the ad and the platform is paid to provide the ad. Then all parties are happy.

Anyway, the devil is in the implementation details here, but this doesn't strike me as a common case.

For ads I see in places I paid not to see them, I add all the vendors to my "never buy from" list when this happens.