Feedback won't help either-- a scammer can just make 2 accounts and leave positive feedback for himself.
We used to have a rule that you had to post a pic of item with your screen name and date--- that rule doesn't seem to be upheld anymore---- on expensive items I always ask for more pics of items with "unique" things for the next pic--- example, if its a rifle ask for something unique added to the pic such as a piece of mail with their address on it in the pic, or a can of soda, or sunglasses, car keys, etc---- you can usually tell if these things are photoshopped into the pic.
Always be prepared to loose $ if you aren't dealing ftf. Dealing with long time members almost guarantees you wont get scammed as they usually get found out fairly quickly