my friend once sold a broken xbox to a gamestop
they didn't check if it worked
oh, and another somewhat related anecdote:
i bought half-life 2 episode one at best buy, installed and registered it, realized i wanted regular half-life 2 so i returned it and got half-life 2 instead.
BTW! i can still play episode one, and whoever buys my used copy can't because i used the registration number. lol