What about voting/rating ads? I've seen it in a few places, and it seems so simple -- someone has to have information on how it worked out in practice.

I would expect that having an easy, obvious rating meter on each ad would work in two ways. First it could improve targeting by having the user reject ads on a case-by-case basis. Second, ads that get rejected by a wide range of user types can be determined to be bad in general (ugly, offensive, annoying) and thus removed from circulation, automatically.

Does anyone know why this isn't in place more? (Or perhaps I just haven't noticed it?)