personal incredulity is annoying. "I don't know what I'm talking about, so you're wrong, simply because you can't prove it because someone else said it and they could be wrong too"
What kind of circular logic is this? Good god. How would you ever learn anything that way? Might as well just be an idiot since everything you know that you learned from something else could be wrong simply because someone else doesn't know what they're talking about. Woohoo.