Most of my friends are big fans of heavy metal, but I abhor it ardently. I can match your example by saying heavy metal is unduly overrated, plus I do happen to think it sucks. One part of my head feels inclined to say that a judgment of sucking is a necessary component of the judgment of overratedness. However, I also think Finding Nemo is overrated, but I don't think it sucks. This leads me to think there are degrees of overratedness; i.e. my tastes place Finding Nemo on a much higher position of enjoyability than all of heavy metal.

My friends who love heavy metal will accuse me of committing your proposed fallacy; they could say I'm not justified in saying heavy metal sucks just because it fails to please me. But if someone else says Finding Nemo sucks, I won't blame them, even if my dislike for it doesn't go that far.

It's difficult to name a formal fallacy of personal tastes. It's one thing to detect a flaw in matters of true/untrue, but quite another to say that there can be flaws in matters of like/dislike.