Sluttiness, as popularly perceived, is:
•External. A woman looks slutty, she dresses slutty, she acts slutty. Whether she feels slutty is not something we generally talk about.
•Indiscriminate. We seem to draw very little line between “will have sex with multiple people” and “will have sex with anyone and doesn’t care if it’s an alley cat.”
•Mysterious. Why is a slut slutty? There are some attempted answers out there–need for attention, trying to get something from men–but most often she just is. It’s a character flaw or something. Just as a slut’s internal experience of sluttiness doesn’t get talked up much in the popular narrative, neither does her reason for choosing the slutlife.

[…]

Here are the things about horniness that seem to make people nervous:
•Horniness is internal. It’s defined entirely in terms of a woman’s experience of her own body and feelings.
•Horniness is selective. I’m horny for some of the men but not all of the men, and that’s some sort of radical statement apparently.
•Horniness is humanizing. Women get horny just like people do! It’s impossible to get all “woman, she is a mystery” on this; if you’ve ever had that warm tickly feeling in your pants, you know exactly where a horny woman is coming from.

“Nervous” is an understatement. These are the things about horniness that drive people–male and female–to completely deny that women’s sexual desire exists and matters.