Well, I'm also looking for the perfect solution to this problem and don't think I've found it. What is crucial to know here is what her shower is made of. If it is fiberglass, abrasive products will only make the situation worse. That bristle brush or any abrasive cleaner will be creating tiny scratches that will hold the soap scum,etc and it will never look clean. I'm thinking with a ten foot tall shower, she probably has it tiled, which should make that less of a concern.

Right now I use Simple green and a special cloth will little nubs on it for one of our fiber glass tubs, which works quite well. Our other tub shower (also fiberglass) doesn't seem to respond to that same method. I've used a number of soap scum removing products and just resort to going over and over and over until I feel it is as clean as it is going to get.