5. Left 4 Dead
This issue became apparent in the first game, and unsurprisingly, seemed to spread - much like the zombie infection itself - even more prolifically in the second game's multiplayer offering. It is a shock, though, that a game this silly - and therefore one you expect would invite a lot of casual gamers - is so rife with elitism. Play the game for the first time and you'll be torn to shreds if you don't know the best weapon for a given situation, or don't know where you should camp; it's not uncommon for players to kick their less-experienced team-mates, which just seems childish and precious. Also, idiotic teammates with oddly over-inflated egos prove problematic; if they get themselves in a jam and you don't save them in a time they deem sufficient, you're going to be chewed out in the least, and probably booted. That said, it is a great online experience if you're lucky enough to get some randomers who aren't idiots, or better yet, get a few buddies to jump online with you; it's the best way to enjoy the game.