It took me a lttle while before I learned to refrain from accusatory nabobbery (well, most of the time), but fwiw, this is how I try to do it: I firmly believe (though I know many people wouldn't agree) that the character of the person posting at the other end cannot be judged with any accuracy by the tenor or content of their posts. (I've proven myself correct, with the small handful of people I've met.) This works in both directions, too: Just because they "sound" good, sometimes or often, doesn't mean they are of superior character, either.

I think if you met most of the people who you think, from posts or writing, are of less impressive or less interesting merit (or even "pompous," "goddammed annoying" or "stupid"), you would almost always be surprised that you had been so presumptuous.