Like "N0t tradeing furst, i dun cayr h0w much f3edbak u hab"?
But yeah, get all of their information, if they speak 1337 do not deal with them, if they seem to be immature do not deal with them unless you talk to the parents, search their name/aim SN in the theft report forum, and make sure his feedback is legit (ie. look at location, if everyone is from "*941* in da house*, please, do not deal with him and report it. Also, look at join date/how many posts the person has).
Im pretty sure this is off topic, but it should help someone.