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-pa

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.