Worst/Most harmful quality in a team player?

In multiplayer team games, what is the worst (or contra productive) qualities a player on your team can have?

I personally believe it might be someone who decides focusing on culture and policies (ie calls dibs on all the cultural CSes, all Wonders that have at least +1 culture), because policies really help out the TEAM, right? I'm sorry, but the Warlord AI just jumped ahead of us in the science department, but your precious culture will do... something.

Someone who can't even beat Warlord difficulty AIs,