Neg hits are for women who think they are the most attractive women in the world. They're meant to kick them off the pedestal they've put themselves on.
A neg hit is an insult disguised as a compliment. Example, "Those are nice shoes, my mother bought a pair like that recently" In other words, her shoes are nice because an old lady you know wears them.
Neg hits are not for women who are trying to better themselves or their lives. When you give a neg hit to a woman who isn't on a pedestal, you just make yourself look like an a55hole.