Ok I think I'm done with trying to play with randoms at Expert level on L4D2 now. It all started off so promisingly, we got through Dead Center chapter 1 easy enough only to reach chapter 2, first try, and have a horde arrive right outside the saferoom door. One of the good players left and then after that *sigh*. Had experience with a griefer who came in and shot everybody mid-level before leaving and playing most of the time with bots. Really it's just the level of patience that randoms have, if they die first time round they just back out immediately. Don't play expert then! You're gonna die, simple as! And there's little chance of finding other people to join the session because L4D2 on Xbox Live is pretty much dead, particularly players willing to play on Expert.
What I want is to play with some mates, but there's no chance of it happening as I think nobody on my friend's list has L4D2, or plays it regularly. It sucks.