It depends what the class is and if the professor knows what he is talking about. In other words how much he was really involved with it. If he is a just a fan, most likely i'd give him the same credibility i'd give myself, which is not that good.

I'm a bboy so why the hell would i ever take a class learning about the roots of bboying from someone who is not a bboy...when i could just go to say the originators of the dance in my country (or my local scene) and do the same. Infinitely cheaper and more interesting.