[kenhwang]

I'd say there's two kinds of publishers.

The "good" publishers will simply charge more per ad and do more hidden proof of trustworthiness, such as being more open to code audits/transparency, more user tolerable ad practices/product deisgn to minimize bad behavior/increase tolerability, or better ad targeting to simply demonstrate more effective conversions. Think Facebook (the tradeoff here is they know a lot more personal information about you to be able to do this).

Unfortunately, most ad publishers fall into the "bad" camp where they know they won't receive payout for some portion of their ads, so they increase the amount of ads shown to make up for the shrink or simply show lower paying ads that have more lenient verification requirements. This is more what Google does/encourages.

My experience is advertisers would love to show less ads with higher conversions, because it makes their lives way easier. But they can only buy what's offered, and there's a lot of cheap user hostile publishers desperate for ads (even most of the ad strategy suggestions in this thread are pushing for more ads) and very very few high quality ad publishers.