yeah they will let you replace it probly for the same game, but that's if you are lucky and they have that same game used in your store. very ymmv
If they don't have the same game instock they have to give you store credit for what you bought.
Used games have the same defective return policy as new. If it doesn't work, bring it back to the store or send it back online. You'll either get it replaced with the same game or get a credit.
BTW, all discs are resurfaced so the likelihood of getting a defective game is very low.