Here are some the requirements from Lethality's recruitment post, I whole-hardheartedly agree with and shall be submitting for perhaps adding to our own requirements (they have a zero tolerance on these and you will be dismissed from the guild):

Trolls
Anyone who likes to Troll others, on any Community Social Site, within any Community game, Community forums, or Community TeamSpeak are removed from the Community and its games. It’s not who we are, nor who we want to be.

Debbie Downers
Any members who sours the spirit of our community through consistent negative or disruptive behavior are removed from the Community and its games. We’re here to support one another and have a great time. There’s no room for Debbie Downers.

Taxman

"Any group is weaker than a man alone unless they are perfectly trained to work together."
- Robert A. Heinlein, Starship Troopers