He may even hate it. As much as the movie may do to enlighten a person to how technical jazz can actually be it, it goes equally far in showing how mind-numbingly tedious it can be as well. If a person were already inclined to dislike jazz I feel like this film would reinforce that. And the opposite could be true for a person who leans towards liking it.
Just as Teller never gets his applause, Fletcher's methods are never vindicated by the film. We can't really say "he was tough but he knew what he was about". We can only really say "he was tough". I wasn't sure how I was supposed to take his playing in that club Teller stumbles across. Is that a gig befitting a prestigious player or something much more humbling? He is a teacher at a top-tier school, but even that did not necessarily indicate to me a position based on merit, because his personality may have had a lot to do with him getting that job. We don't get to know.