Originally Posted By: FastEddie
Sounds like the hard water etched your glass, if that's the case:
Cerium Oxide, glass polishing pads (I LOVE the ones by Car Pro), and a rotary or dual action polisher. It's not a quick fix by any means, but where I live, you could try vinegar, clay, barkeepers friend etc all day long and never make a dent in the spots because they have etched the glass most of the time (terrible water).
+1
For starters, I would try CarPro's Ceriglass on a foam polishing pad. If it doesn't work, then step up to the glass pads.