So basically, it just means that the more mysterious a woman is, the more attractive she is... maybe?
Not exactly a wrong phrase XDD A girl has to have some secrets XDD
Just as long as the secret isn't that she's really a man.
I have loads of secrets. I must be extremely attractive.
Though, I understand your reasoning.
It really depends. A lot of guys love the wholesome girl-next-door, since they're available and sweet. The mysterious girl is exotic and, well, mysterious.
I don't mind them.