Clean really dirty shower glass?
I scrub it first with a soap (you might need something like Scrubbing Bubbles) and sponge to get the grime off, then I follow that with paper towels and a basic glass cleaner.
Again, I am recommending you check with Home Depot...
Norwex Descaler with a Bathroom Scrub Mitt or Spirisponge!
First clean scum with soap pads or steel wool, then spray multiple times with wet & forget it. May take awhile to get it clean but worked for me.
20 Mule Team Borax powder on a wet microfiber rag should remove soap scum. Follow with three generous coats of Rain X (available in automobile supply section of Walmart, etc), which causes water to bead up on the glass.
Squeegee any water droplets from shower glass after showers and wipe remaining droplets with a soft towel.