you can recognize them and point them to bandit sites directly.
Maybe this could be done by enlisting normal, bored users as "Deputies" who scroll through a list of sites and mark them for "Sheriff review." You know, like Mechanical Turk, enlisting the work of the bored masses and all that. The list of sites up for Deputy review could be shortened based on marks in earlier reviews.
If there are hundreds of spam sites, personally contacting and explaining stuff to Sheriffs is quite a bit of work…that's all I'm thinking.
EDIT: And don't Sheriffs wear stars? That'll be confusing.
EDIT2: I noticed that you wrote an entry about graphmastur's blog post. I had just figured that graphmastur was Pieter. Oops.