I had the unfortunate chance of meeting a real psycho through CL. I was selling a bike for $75; Schwinn, solid, nothing fancy. The Buyer had a list of questions 1, 2, 3, ,etc for me to answer. Said he wanted to check x, y, z. At first I was receptive, tried to answer his questions. It got annoying. So, I said, its not the right bike for you. This jerk did a search on my name and sent me an emailing; saying, "you went to college here, you work here, you live here...etc. " No direct threat; just a "hey, I know these things about you." Weirdo.