I do a lot of reading online. Some of it is one-way - that is, it's a piece of text, and the only interaction comes from someone reading it - but a lot of what I read is interactive: message boards, comment threads on blogs, things like that. These are basically conversations, but conducted in text rather than sound.
Generally, I like this approach. Text conversations tend to be better thought out than spoken conversations, and if you're not sure what someone just said, you can go back and reread it. There are tradeoffs, of course - since you can't see stance or expression, it's hard to tell when someone is being ironic - but if you're willing to extend the benefit of the doubt and/or ask for clarification when needed, that doesn't have to be a problem. Also, I like to sit down and assemble my thoughts into a unified whole - and I can do that in text a lot more easily than I can while speaking.
Recently, though (say, within the last year), I've encountered several situations where one or more people takes advantage of the medium to be extremely rude. When someone pointed this out, they did not apologize; instead, they continued to be rude, or became even more rude. (I realize that this is actually quite common, but I generally stick to sites with good moderation and well-developed communities; so I don't run into it, much.)
I don't generally interact with those sorts of people. I don't need the grief, and there's never any benefit to it. Having encountered two of them in relatively close succession, however, I find myself considering the pathology of the behavior.
So, without further ado, I present the Top Five Signs That You Might Be An Asshole:
5. A lot of your fun comes from making things less fun for other people. (This doesn't mean you're superior; it just means that you're mean.)
4. You focus on winning the debate and/or showing how foolish your opponent's belief/opinion/stance is. (This is fine in an actual debate; but treating every conversation as a debate is a mistake. That's true even if it's only about a certain topic. This behavior is doubly foolish, as it fairly well guarantees that not only will you not get anything out of the discussion, but you won't convince anyone else, either.)
3. You defend your behavior by saying that people spend too much time being polite instead of saying what they mean, and/or complaining about people being "politically correct". (It is, in fact, perfectly possible to polite and clear at the same time.)
2. You're certain that you're strong, and the fact that other people get upset with you demonstrates their weakness. Alternatively, you're certain that the reason people get upset with you is because they know you're right (which is basically the same thing). (Anyone will get upset if someone pushes the right buttons. Also, can we stop with the lame metaphors and self-aggrandizing imagery? Honestly...)
And the number one indication is... ::drumroll::
1. You say things like "everybody makes mistakes" or "I've been wrong before" but somehow there's never any possibility that you might be wrong about the topic at hand. (Um, yeah. Really. Huh?)
Also, you get bonus points if you make a habit of communicating poorly and then acting smug, offended, or both when people misunderstand you or ask for clarification.