2. Angry Girls
She is the Other Girl.
There are a number of theories as to why the Other Girl appears so frequently as a foil to the Angry Girl. Classically, evil often appears in the form of beauty, like the femme fatale. In YA, she has a lot to do with our preconceived notion of popular high school girls.
Mostly, though, I think the Other Girl has a lot to do with insecurity. The traits
that make her so eminently hate-able-- her beauty, her grasp of fashion and cosmetics, her social skills-- also make her exceptionally competent. She gives off an extreme aura of having her act together.
And speaking in generalities, young women-- myself included-- don't feel this way. Everyone has one aspect of their appearance that they're constantly trying to tame. Everyone, that is, except the Other Girl. She has already conquered the art of looking fabulous.
But the Other Girl's attack goes way beyond the average insecurities. It is based on a simple assumption: that readers and writers are intrinsically more insecure than other people.
This may at first glance make sense. Readers are traditionally considered socially awkward outsiders, who certainly could never master fashion or cosmetics. They identify pretty heavily with the Angry Girl. Readers would never indulge in a beauty as artificial as the Other Girl's. Instead, they have their own inner beauty that has nothing to do with hygiene or cosmetics.
This possibly explains the sheer over-the-topness of the Other Girl's dour personality. She's the antithesis to the reader.
And this is a stereotype just as narrow-minded and implausible as the Other Girl.
I am a reader and a writer, and I don't leave the house without mascara on. I have a hair-makeup-clothes board on Pinterest as well as storyboards. I know I'm not the only one like this.
Ultimately, that's the beauty of stereotypes: that they're not real.