I don't have to find counter-evidence. I just have to ask HIM to show evidence of his extraordinary claims. Arguably, by pointing out how vague his actual evidence is (and putting it in context, e.g. 'world martial arts champion' == 'successful exploiter of loopholes in an obscure Chinese kickboxing event') I'm sort of doing what you say, but the claim that Ferriss should be taken seriously until comprehensively debunked is rubbish. Who has time to wander around debunking every semi-popular crackpot on the web?

All I know is that when Ferriss's claims intersect stuff that I know about I can tell he's full of it. This doesn't raise my level of faith about anything else.