believes everything you say is the truth
No, but seriously:
Personally, I'd say the biggest traits I look for in a friend are:
Empathy/acceptance-Regardless of where I came from, I'm here now and I need someone to understand my position/point of view.
Integrity-do what's right; legally and morally regardless of the cost.
Trust/honesty-- to the point of crossing emotional boundaries in order to help me. For instance, he/she notices I'm displaying prejudice/bias or stonewalling and is not afraid to let me know by insulting me but doesn't use this as the only means to communicate with me. However, for this to be possible there must be a history between us and and an understanding.