Statistically the more you sleep around, the more desensitized you become to pair bonding. This makes promiscuous types much less suitable for long term relationships.
The bad boy fetish comes from a mutation of in the instinct to value the male capacity for violence. They think that if a man is dangerous, he demonstrates a high capacity for violence. Couple this with the perceived confidence (rejection of society's rules), they think such a man will protect them, dominate them, make their lives easier by making decisions for them using their primal male authority, and fuck them like the cavewomen sluts they are.
Objective. Physical phenotypes are related to intelligence and behavior. observed in every subspecies on the planet. you can tell if someone is nice by their looks.