Never before have I written here about cleaning ANYTHING, but I just couldn't resist passing this on..... For 22 years I've battled glass shower walls/doors, and short of cleaning them every day (what sane person would ever attempt this???), pretty much came to the conclusion that it was all about intense aerobic scrubbing. (Great for upper-body strengthening!) I'd tried all the grocery store chemicals. What eventually worked best was the straight edge of a hard Cuisinart spatula -- the one that came with the original model, which was a gift to my late husband before I even knew him. I wore that down to a nub! Wore myself out wearing it down to a nub!
So today, a lightbulb went on in the brain, and I thought I'd try googling "soap scum shower doors", with results nothing short of miraculous. The answer is Spray-n-Wash. Spray it on, rub it in, let it sit for about ten minutes, take a scrub brush to it, rinse, and voilà . CLEAN. And I mean REALLY CLEAN.
So that's it. Get out that Spray-n-Wash and clean up that glass!