Why Do Some Relatively Young Women Smell Like Old Ladies, But Others Don't, and How Do the Former Get Rid of that Smell?

I know a few attractive women in their 30's or 40's who smell like old ladies, meaning they have this dried fish smell. It's a bit subtle and you have to get close to them to smell it, but there it is. Paradoxically, I know even older women in their 50's, 60's and 70's who DON'T have the old lady smell.

It's not always a dried fish smell. Sometimes it's something else, but not shit, but it smells bad and off-putting, like stay away from my vagina.

Thoughts?

Edit: To clarify, the odor doesn't necessarily emanate from their vaginas. Also, not their hairspray. It comes from their bodies, at least in part, and it doesn't smell like regular B.O. For some reason, the smell evokes death and decay, in my mind.