Isn't it enough to just realise that, whether or not you would equally slag off men for doing it, it comes off as misogynistic?
Also, how many men do you see with obvious cosmetic surgery? There's Pete Burns and George Michael and er...
By slagging her off, you are basically feeding into this message that women can be commented on. Slagging off men as well is sort of by the by, because it just doesn't happen in the same way in our society.
Beyond that, isn't it just nicer to NOT slag people off? People in general. Not just men or women. Their appearance doesn't affect you at all, so why bother commenting?
I'm by no means perfect on this front, surely, I slag people off in my head, out loud too, by the way.