And then, just to make sure you realise it's a pre-owned game, they occasionally put a sticker on the front of the manual and on the disc too.
The worst I've seen, though, is a store in Australia called JB Hi-Fi. For pre-owned games, they have these huge triangular stickers that span around the front, spine and back of the case. They cover about 2-3 inches of the top of the spine, and a good portion of the front and back too. And they're the stickers that don't peel off easily, leaving sticky residue all over the case. One of the reasons I've stopped buying pre-owned games from them.