Our daughter sits on our leather sofa everyday after getting out of the
shower. She wears a robe that is a bit damp, along with wet hair. I
have noticed the sofa getting a white-ish look where she sits.

My wife says that moisture is good for leather and doesn't believe that
the wet robe is causing the fading.

Can someone tell me if this daily routine is bad or good for the
leather?

Thanks in advance.

Yes, it is bad for the leather. Water leaches the oils out of leather
and causes it to dry out.

Sophie

Yes, it causes the leather to turn white.