When the cops work a sting, it's 40 year olds pretending to be 14, not the other way around. Until the moment you discover they're underage, you're not doing anything illegal ON THE INTERNET.
My problem is that I can't tell a 12 year old from an 18 year old when I'm staring them in the face, and in real life encounters the law doesn't give me that benefit of the doubt.