Seem to remember a thread on cleaning shower glass once before. So please forgive me if I'm repeating myself. Have you tried WD-40? I never would have believed it but it actually did an outstanding job on ours and we've been able to keep it clean with regular stuff since.
DW read it somewhere. Sprayed it on the glass, let it sit a minute then wiped it off. The glass was 'milky', 'fogged' etc but was clean and clear afterward. We had tried several of the usual cleaners over the years since we purchased the house with no success. It's in our master bath off of our bedroom so not many people saw it. Nice to have it clean however. Can't guarantee the same results of course but it worked for her. Now we just clean it with regular cleaners. Snopes doesn't seem to have an opinion but it does say it's a petroleum-based product and the main ingredient is >60% naphtha. FWIW