I haven't read the Harry Potter books (much to Jen's annoyance) so I don't really have a strong opinion on the characters. Their proclivities don't matter much to me, and the activities of fictional characters in general aren't high on the list of things I worry about.
J.K. Rowling recently announced that one of the heroes of the series, Dumbledore, is gay. The thing is, though: he's not.