Yeah an unscratched used game is about as good as new to me. You have a 30 day return policy at Gamestop actually. 7 days is for a straight up no questions asked return for a full refund. After the 7 days, it's same game only.
After 30 days, you're stuck with it, but if it's damaged you could always buy the same exact game again and swap them out, and if you're really clever, ask for 2 copies of the receipt and return both. Tell them you need two copies for...I don't know, tax purposes. They don't scan the receipt or anything.
I did this with Monster Hunter for PS2, but if you saw the first game disc they gave me you wouldn't blame me. I happened to wait over 30 days to even look at the game. Had built up my PS2 collection. Then I looked at the bottom of it and I've never bought a used game that looked this bad.
So I bought another copy, got a 2nd receipt with it, returned both games at two different gamestops, no problems. I did actually play the game after I got the 2nd copy. OMG, don't buy Monster Hunter unless you actually have your PS2 hooked up online still, which I don't. It was pretty lame anyhow imo. More like a Cabela's hunting game, and lots of stupid gathering missions, like go find some mushrooms, go find an egg, go steal an egg from a dinosaur bird, shoot x number of monsters, shoot x times 3 number of the same monster 3 quests later. Not much fun at all on the single player quests.