...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.
That's a great idea! I've been thinking about how it would be possible to classify "personal" sites using a common identifier...lack of ads would be a good one, although that would still grab the majority of corporate blog sites.
That'd certainly be an interesting idea, and it'd probably find quite a few intriguing sites and pages.
That said, it also wouldn't be perfect, since quite a few small and personal sites do have ads for whatever reason. Usually because the author thinks hey, even a 0.5% chance someone clicks on an ad will pay better than no ads/a donation link.
