This tumbled travertine shower was extremely soiled. There was mold growing in every crevice of the grout and stone. The surface was deep cleaned repeatedly and treated with multiple treatments to remove the live growths and other residues. Once cleaned the surfaces were sealed to help with future cleanings.
It's up to you to keep you shower clean. Drying it out, squeegeeing the walls and glass, and having proper ventilation are some great ways to keep your natural stone shower looking great over the long run.