My copy of Link's Awakening DX has the previous owner's initials marked on the back of the cartridge, but it works fine. If I'm buying a used handheld (GB/GBC) game, I test it first.
I saw a copy of Pikmin 2 at a grocery store that used to rent out games. Things seemed okay, but I think the disc was scoffed or scratched a little. I don't remember whether or not the manual was still there. Needless to say, I didn't buy it.