No, it never crossed my mind, and I don't think it's a good idea. It would be a pointless waste of time. So what if you called somebody out? At best, they open a new profile and go at it again. At worst, you mistakenly call somebody out who isn't actually a pedophile and cause him undue hardship (and/or get yourself sued).

Kids are already aware of whats out there. A lot of them have grown up with this technology and are probably more savvy than you.

If you want to help kids, then do something in your community. Don't waste your time playing internet cop.