When I worked at GameStop, I made sure to sell all PS3 and 360 games used. The only games I would sell new are Nintendo games. It was easy.
Nintendo customer: "Ah, it's only five dollars more, plus you get the comfort in knowing it new and has never been played before."
HD customer: "It is basically the same thing as a new copy, it's only five dollars cheaper. Plus, if you don't like the game, you have seven days to return it!"
This is partly the reason that Wii software sells.