The reason newspaper is good for polishing glass is the ink. It acts as an ultra-fine polish. I had some problems with streak wipers and such, and polished my windshield with newspaper and then clayed it, and now my windshield beads like there is Rain-X on it, as long as I clean with 20/20 once a month. The only way the newspaper is going to scratch you glass is if there is grit on the paper or on the glass, so make sure you wipe the windows down well before you use the paper to polish.