I've attended a number of seminars with black belts that were trash, most notably ones where the subject matter was something like that.... In fact, I've repeatedly tapped a black belt at his seminar with leg locks that taught nothing but leg locks (This was when I was much less experienced as well). For some reason, leg locks are in fashion right now and people want to teach them even if its not their thing. This can cause results to very...
A guy like Joe is going to have promoted a huge amounts of black belts. Your gonna need to be willing to drop this guys name if you want to know if anyone has heard of him. Its very possible that a guy is pretending to be his black belt but no one can give you feedback without more info.