Aliasalpha: The only remotely safe way to buy a used 360 is to get it from a shop that does trade ins, that way you can at least take it back and hit them with it if it turns out they sold you a banned unit (and they should bloody well know the difference). You might still be able to pick up a good deal on the older white pro model that would be worth it
You would THINK that, but I actually asked some of my friends who work for Gamestop and some of them who work at the store I go to....they don't test them. They don't do any kind of internet connection check to see if it is legit hardware or not. They just hook it up to a screen and make sure it doesn't red ring.