Certainly I think sometimes you have to take a calculated risk and leave some things unsaid, but I think being aware of how things are going to be interpreted and choosing your words carefully can make a big difference. And being aware of the way things can be misinterpreted on the internet means not getting upset when someone inevitably misinterprets you.

People who don't read everything they're arguing against (unless they at least acknowledge that's what they're doing) annoy me :P (Though people who write unreadably long screeds and get annoyed when others don't read them annoy me too. I at least cut mine :D)