You people are all insane!!! lol
And yes, I have personally used facebook to weed people out of a pool of "already hireds." Basically, about 140 or so people had been hired to work as summer teachers for a program i was a site director for. They were all undergrads at specific schools. We had sort of a "draft" meeting where we could pick our favorites and negotiate. Well, prior to that meeting I got on facebook and eliminated the ones who were wack jobs. (I also had somebody on GC help, LOL)
Shady, yes, but research is legal!