There's this group of three players in a look for group (5 player group in WoW) that always vote kick healers after a run. Majority vote seems very good to eliminate grief especially when you join this party as a healer. (sarcasm).

In an MMO it is not a very good idea to leave too much power in the hands of few. Much like Platinum_Dragon has alluded to, I would not put vote kicking in an MMO, but it does have it's place in multiplayer games that have hundreds/thousands of servers to choose from. In multiplayer games if the majority, sometimes a complete server vote is required, all vote to remove a player from the server that player probably did something to deserve it and they also have plenty of other servers to choose from. In an MMO you only have the server of which your character exists and it should be left up to the group leader to determine who stays/goes so the quality of the group leader is what matters most, not the dissendent majority.

If we are talking about an MMO with a persistent world:
http://www.gamedev.net/topic/628501-are-open-pvp-full-loot-sandbox-mmorpgs-still-possible/page__st__20__p__4963497#entry4963497

Relevant, as random PKers and griefers are similar in that they both are despised and need to be brought before justice.

If we're talking about a non-persistent game like L4D2, then I would suggest a reputation system. Players can suggest whether or not other players were griefers or unskilled. Then, people will automatically be grouped with similar people.