I think its really fun to argue with the Jehova's Wittneses when they try and peddle their religion at my door, does that make me a bad person?

and I wasn't an accident, they wanted me they just didn't realize it at the time.

I'd say that seeking an argument for the sake of the entertainment of having an argument is, at the very least, impolite (unless the person you're arguing with also wants that type of entertainment). On the other hand, there is nothing wrong with having a discussion with someone who approaches you with the intent of convincing you of their way of thinking.

I'd say that the difference is that in the former case you're wasting someone's time for your own enjoyment, and in the latter you're making an honest attempt to either change the person's mind or find out more about their beliefs. If you find yourself arguing in a badgering way or phrasing things in the most inflammatory way possible, then I'd say you're probably not really having a discussion, you're just harassing someone for fun.

I'm sure that some people will say that Jehovah's Witnesses are "asking for it" by coming to your door in the first place. I would disagree. They honest believe that they are trying to help people and, in that sense, are probably more morally justified than, say, a salesperson who comes to your door. You can politely turn them away (or just not answer your door), or you can put up a "no solicitors" sign.

But being rude or badgering to someone sincerely religious can only give atheists a bad name. We don't need more of that.