Hmmmmmm! Well, I think that Buffy is in some senses an excellent role model, and in others not. In Buffyverse, essentially all characters are flawed to one degree or another, which is precisely true of all people. I'd be hard pressed to think of something truly negative to say about Tara or Amanda besides being usually too self-effacing, but they are human and, by nature, not perfect. Most of the characters have differing levels of unkindness, cruelty, selfishness, bigotry, hubris, egocentricity, dishonesty, narrow-mindedness, criminality, vanity, and so on. Whedon's main characters are usually painted in varying shades of grey. I agree that a hero is a hero based on heroic deeds, but only the most unexamined life can be seen as praiseworthy in all aspects. We humans are by nature flawed creatures, a thing Whedon knows.