I occasionally make guesses and assumptions based on the available information, but I definitely make it clear when I do.
That way if someone finds a hole my argument, their correction carries less weight!
Well I've noticed you stand firmly with what you're talking about, but since it seems like you have the knowledge in whatever it is that you put your 2 cents in, I say you're just like me.
What pisses me off are people that talk about something like they know the subject matter, but they really don't. Frauds get revealed if you prod them a little.