I hesitate to say this, but I think there needs to be a proving ground for new players.
If you go though some of the games being played, it becomes quite obvious that a lot of games are being ruined by new people. It's not that these people are trolls, or intentionally looking to derail games, it's that they seem to "playing" more than attempting to draw.
If you've ever played a game like WoW, you'll start in an erratic where everyone is just mucking around trying to get a feel for the game. There is nothing wrong with that obviously, but if it weren't separated from the established players, it would be frustrating.
The same thing happens in FPS games where new players lack the experience, and wreck a lot of games while they attempt to learn.
I think there should be a minimum game/point count before new players are able to participate in regular games. This idea could be paired with learning instructions for better games such as, "looks like you didn't get many points on that last game, try keeping your descriptions short and to the point"
I don't think anyone should be faulted for poor drawings, or descriptions, but as this site grows, more and more games will be faced with new players. If every time a new player joins and uses the opportunity to mess around instead of play the game, we are probably going to see a dramatic rise in poor quality games.