Have you ever bought a new game and had to return it because it was damaged or wouldn't work?
I was reading about some people's troubles with Halo 3; apparently the discs come loose and get scratched in the package very easily. It made me think about my own experiences. I've been pretty lucky, except for a couple of times when I bought games off eBay that didn't work. There have been a few other close calls, like Dark Cloud, which hangs up at a certain point early on.