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

I think when one does make up regularly and doesnt have it on one day, it can easily be seen... I can tell if the girl uses make up regularly or not if she is not in make up. I know i am not makin much sense, however i dont mind makeup as long as its not daily routine, coz then i'll get scared if she doesnt have it on :d.