Yeah, I think my big problem with Xander's early behavior is that we don't get to see the harm that it does, we don't get to see very many consequences for the way he behaves, etc. Everyone just rolls their eyes at his slut-shaming comments and goes on with the episode, which gives the message that his comments are harmless. I definitely think it would be unrealistic to have Xander never be sexist, but he's one of the "good guys" of the show, and I don't like when he does awful things and nothing in the show calls him out on it or makes him face any consequences.