As far as teamswitching I agree that it is a huge problem. I have sent jackie a couple ideas but I think we need to decide as a community on what to do about it.
I am guilty of switching to the winning team because mine sucked so much, but I have gotten better at this and it is easier when there are other regulars in the game that help you relax.
I suggest disabling switching to the winning team if the score is over a certain threshold (or maybe just in general?)
Another thought, though not practical... is that when one person screws you over it suddenly becomes 9 or 8 v10 which isnt too bad, but the infected will slowly cut you down to 5v10 which is kind of ridiculous and not the way l4d2 was intended. In a normal 4v4 when 2 people die the round is pretty much over, however this is kinda disproportionate to a 5v10. A solution to this would to only allow a certain number of infected to spawn based on the number of survivors. ie: 5v7 or 6v8. Another option could be to raise the respawn time
idk, what do others think?