[quote name='crunchewy']I bought a copy of Mario Power Tennis from Gamestop and the disc looked horrendous. Lots of awful looking scratches running around the disc in exactly the way you don't want them to. Yet the game plays perfectly. We've not had any problems with it at all. The GC reads the disc fine and it plays fine. Unfortunately (at least without running/having the ability to run homebrew software) there is no way to be sure. You'll find out eventually.[/QUOTE]
I had a similar experience with a game I got off Gamestop.com. Seeing how scratched up it was I was sure I would return it to a B&M location, but I decided to try it and it seemed to play fine. Granted, I only played it for a few hours, but I decided to keep it rather than return it since I hardly ever see it come in stock at the locations near me.