I found the best way to clean water spots from shower doors. Don’t waste your time trying all the other stuff.
I tried vinegar soaked on paper towels and left it on there for forty minutes. It didn’t work and I now smell like vinegar. I tried Comet with a scrub pad, it didn’t work. Then with little effort and no smell, I used glass cook top cleaner. It worked like a charm. My shower door looks brand new.