I've never realised how i bought them myself to be fair xD, but I guess looking back, and my habits now, it would depend on which Console i'm buying for. My habits have varied over the years, but i generally have this kind of routine i go through:
If i were buying, say, a DS or 3DS game, i would just buy a second hand version, because they can be in any condition( that is 2nd hand approved) and it will work perfectly without breaking or crashing whilst i'm playing. Since it is a cartridge type, it wouldn't be too harshly knocked up anyway if it was second hand because you could tell if it doesn't work anyway and retail stores would check that.
However if i were to buy a Wii game, which are discs, i would buy them first hand if possible, so that they are guaranteed to be scratch free, and if i were to buy them second hand i always get the disc repaired from GAME so that i don't end up getting angry if the game didn't work when i take it home. I always get the dis repaired because sometimes when i used to buy second hand games from shops, they said it worked when they tested the games, but when i got back home the games didn't work and it really annoyed me >.<.