What makes Holden dislike Ernie, the piano player, even though he is an obviously talented musician?

Holden dislikes Ernie because he thinks he's a phony.

Anyway, when he was finished, and everybody was clapping their heads off, old Ernie turned around on his stool and gave this very phony, humble bow. Like as if he was a helluva humble guy, besides being a terrific piano player. It was very phony--I mean him being such a big snob and all.