On Chicago we have a frequent CL seller who is widely suspected of being a thief, or at least of selling stolen bikes. At minimum he's a complete jerk. He posts frequent ads with photos showing no detail, describes them in very vague ways like 'rides really nice' and also with no detail. Then if you email or call him (I've done both) and ask for details he abuses you. Apparently he is very slippery when you deal with him in person as well, and the bikes show signs of fresh rattle-can paint jobs. So he really seems to be hiding something, like anything which could specifically identify the bikes.

He'll never be caught so if someone on CL wants to 'jam a stick in his spokes' I'm all for it.