A good debater isn't swayed at all by the other party's (note that I didn't call them an opponent, more later) viewpoint. This absolutely requires them to be a jerkass, for a person that's open-minded would stop to consider the other side as more than something to refute.

I rather think that debate, for the common person, is an absolutely useless skill. We would all do well not to get into the debate mindset, where our goal is to win, to trounce the opponent, and to approach every conversation like a battle. I find that attitude to be very immature. I find that attitude here quite often, and it does make staying here a chore. Unless you're in debate class, a trial lawyer or a politician, there's no need for debating skills in day to day life. Looking up the other side of things just so you'll know how to shoot them down is a waste of time and a waste of life.

If both debating parties are approaching their conversation that way, why bother having it? Neither of them are going to open their minds, let alone change them. Besides, who the hell are any of us to impose our viewpoints on anyone else, anyway?