The stone scrub polished the marble???
Sorry I should have clarified.
MOST of the time, in showers, the marble is not actually damaged. The dead giveaway for chemical damage is run marks from the shower head area on down. Most of the time you just see spots everywhere. It's the water drying on the surface of the stone because the homeowner doesn't squeegee. These spots don't clean off. You can polish them off with a polishing compount because the acid in the compounds will eat away the mineral deposits and the abrasives will re-polish or ensure that the shine is preserved.
With Stone Scrub, it is abrasive enough to remove the junk from the surface of polished marble, but not too abrasive to disturb the polished finish. So what you're actually doing with the stone scrub, is skimming everything off the surface to reveal the marble underneath, which was basically preserved by the water deposits and soap scum buildup.
Soap scum and hard water looks terrible, but it actually protects the polished finish.
Stone Scrub is a great starting point and a great way to get the feel of polishing a shower without diving head first into polishing powders and diamonds.