I have a shower stall with glass doors and couldn't get them to come clean with ANYTHING. Eventually, believe it or not, what worked (and amazingly so) was a Mr.Clean magic eraser, damp with a little dish soap on it. (tried it without the dish soap and it did nothing. Tried the dish soap on its own, nothing.)
I don't know how it works, all I know is that I'm glad I do know!
Hope this helps ! :)