1) Argues against someone else without taking a stand themselves. This way they can attack others but never take a position that can be attacked.
2) Misrepresents what others are saying, on purpose.
3) Pretends not to understand what someone else is saying.
4) Attacks the person instead of their position.
5) Decides where they stand on a topic just to oppose where others stand.
6) Uses loaded questions to poison the discussion.