I wouldn't call myself a veteran, but an experienced person at the least...
First off, if new players want to get in on a team game, ask when one needs players. It gets your popularity up for other people, and if your good, more people will probably want to play with you more often.
Most team games have PWs on them so that, if someone leaves, someone annoying, and there to screw up the game doesn't jump in. They ask for a replacement from anyone who they haven't had a bad experience with.
If you want to ban password games, make one without a password. 'Nuff said.