EB

Hi. EB tried to sell 2nd hand games to me as new before, and I've heard from many places they do this a lot (the 2nd hands are mostly from 7 day return policy). For consoles it's not fatal if I get a 2nd hand, but for a 2nd hand PC the cd key will obviously be stolen and some pc games don't have authentication during installation, they only make sure no CD key is being used by two accounts at the same time when playing online. So what I'm worried about is being sold a 2nd hand pc game that looks new, but I cannot know immediately if the CD key has been stolen when I get online, until the guy who stole the CD keys plays at the same time as me (at that time it'll be too late to return the game).

Do all pc games come with wrap? I'm looking for crysis 2 & bf3. Most games I bought from them when I was young were gutted and at that time I didn't know they might be second hand, so you know I didn't have a good experience with them. Is shrink wrap a definite give away? Or can they rewrap using factory wrap as well?