We do have control to an extent. If you blend your ads in "TOO well", visitors will be tricked to clicking those ads, you just sent a low quality traffic becuase that user probably closed the browser, and google knows this... now, if you explicitly place your ads separate from your content, users KNOW that it's an advertisement, they will only click if they are interested in what that ad have to offer, you will get lower CTR because less people are interested, but that minority group of people are the people that have better chance of converting. you send them 100 visitors, 5 people end up buying, that is a good conversion for the advertiser and they will pay alot more for your site (this is where I think google's ranking/smartpricing kicks in)
Congratulation man. You are right. Publishers are seeking for organic traffic from search engines and if your site rank well in search engines, then you can convert those quality traffic into cash.
agree. organic traffic is good for ads click, while some social network tools, such as digg.com, do nothing for ads click.