[codedokode]

As I understand, the problem here is that Google wants to run your ads on third-party sites (to earn more), but you don't want to run ads there because third-party sites employ every trick possible to generate impressions even if real user never sees the ads.

If you care about money spent, you should calculate ROI for each third-party site and filter out those which give low returns. And not expect that Google will do that for you.

[makestuff]

I would be surprised if there wasn’t some SAAS offering that did this for you.

[spondylosaurus]

There's a whole cottage industry of ad quality/anti-fraud filtering tools. Some better than others.