NancyLebovitz:

The only gender difference I can see is that a significant proportion of men [1] are apt to verbally attack unattractive women just for existing, while women are more apt to wait for a pass to be made by an unattractive man.

This is true if you judge people's speech and reactions by the usual standards of discourse in polite society, but not if you take into account their actual hurtfulness and the actual level of repugnance and scorn being manifested.

Men are indeed apt to appraise women's attractiveness explicitly in crude and vulgar terms, much more so than vice versa. However, the ways in which women talk about unattractive men might sound gentler and far more polite, but it's naive to think that unattractive men don't get the message, and that they don't get hurt just as much as unattractive women who get called by various explicit bad names. Moreover, whenever I hear girls damning some unattractive guy with faint praise, I always feel like it would be more honest if they just scorned and trashed him explicitly, considering the status they assign to him for all practical purposes.

Another thing is that even when stated in the most explicit and crude terms, men's usual complaints and negative appraisals about women tend to sound harsher and more vulgar than the other way around. It just happens that the words typically involved in the former have a much more politically incorrect and inflammatory impact, even though the latter are not any less harsh and damning by any reasonable standard.