I don't think there's anything I wouldn't say to any of the Opeth guys only because I happen to like their music. Not that there's anything I would say to them, either, heh. I met them in Sweden this summer and said "hi" - what else is there to say, really? They're people, like anyone else, whom I don't know. They're talented - sure, but lifting someone on a pedestal because of their position isn't my kind of thing.
Everyone's entitled to their opinions, and I don't believe in holding yourself (or your negative comments) back just because you like something / someone.