I have to put in an agree vote... This i s kinda funny I used adwords AND adsense for a time. When I stopped driving traffic to my site with adwords my adsense revenue dropped precipitously, even though adwords really wasn't bringing THAT much additional traffic into the site. That tells me that the main people who were clicking my adsense ads (giving me money) are the same ones who came into my site by clicking my adwords ad on some other side (taking my money and splitting it between google and the publisher). I ditched adwords because it was
costing more than it was bringing in in both sales and adsense. I seem to be selling about the same with or without adwords, so that tells me the adwords clickers were tire kickers. I appreciated their clicks to adsense but it was a loss when you rack it up beside adwords.
It shouldn't be an issue that most adsense sites are crap. If they are truly crap no one goes to them so no one will click your adword so you won't be out anything.
I guess the novelty wore off google ads jut like it did with banner ads in 1996. People would click google ads because they respected google and the buzz lasted for several years. But I think the surfers just have herd immunity to google ads now.