Cleaning Automotive Glass
AC Delco GM glass cleaner
I used to swear by this stuff, but the key with it and any glass cleaner is after soaking, scrubbing, wiping, let it haze out and dry.
Then use a clean towel and buff it by hand.
My glass shines, really brings out the scratches and wiper marks.
Recently I added a decal to the top of the windshield, which I had put Rain X on and instructions said remove it.
Interweb spoke and said use acetone.
I used it on the entire windshield and removed dirt I never saw in any driving conditions.