...that's a pretty good idea, actually. I'd bet that in some way, shape, or form, search engines probably already have the ability to detect presence of advertising. The question is how they work it into the relevancy formula given that the big two search engines are at the same time the big two ad networks.
I wonder if you can just make an extension to filter these out of the google results. Adblocker extensions certainly don't have a hard time detecting ads in webpages.
