How to respond to the claim of jealousy

You all know how it goes: the second a female passes judgement on another female that some male(s) somewhere find attractive, that first chick is just a jealous and insecure bitch. 

With the advent of the Megan Fox hoopla, I was quite confused about the whole situation of a woman who apparently (no way did I pay money to see Transformers, ha) couldn’t act being popular- especially since she couldn’t really be popular for her looks, since she wasn’t even a natural beauty like Marilyn Monroe (who could sing and act course) or something. 

While plauged with ennui, I searched for an answer. Every where I went, here were the two types of answers from people:

1. You are totally right.

2. You are just jealous, get over her.

Why is it that women can’t comment on other women these days (besides that, as nothing but physical objects, we aren’t supposed to view ourselves/others in that way)? As a bisexual, I particularly find this confusing when a heterosexual male is permitted to call a woman unattractive and I am not permitted, as we both find interest in females.

What kind of response is appropriate for this? I have come to realize that my usual “fuck you, fuck do you know, fucking idiot” is not really an appropriately educated/ing retort.