so what do guys mean when they say they prefer their gf/wives `natural`

I gotta agree with SU here - men don't know what natural looks like if they are asking for it

By natural they don't mean hairy legs and mustaches.

Today's natural is "not too much done up" - meaning lipgloss (chap stick), bronzer and coat of mascara and stylish pony tail.

Most men think Kim Kardasian is very natrual looking :)