Here are the instructions for Dear Niece:
Tilex has a "soap scum" cleaner. Spray it on - leave - go back in 10 minutes with a sponge mop - give it a quick mop - then rinse. Shiny and gorgeous. No sore knees either.
Repeat again before Auntie has to tell you "it's filthy"...
P.S. NEVER-NEVER use an SOS pad on a shower... or you'll be replacing the entire unit - also, no cleanser (ajax/comet) if the unit is less than 10 years old.
How do I know? I just bought a 10 yr old home that the owner used cleansers on. All needs replaced. 3 showers, 6 sinks and 1 whirlpool bath tub. Grrrr....