I have a rear window wiper that left some etching in the window. This is a used car so I am not sure how this happened, other than the blade came off or the wiper arm itself was activated without a blade. The "scratch" isnt deep enough to feel with your finger though. So I'm really puzzled with that. I would like to know if anyone here has removed such a scratch. I called two local glass shops in town. One shop said they only did chips and replacement, the other said it can't be done. (Neither even saw the scratch). I've looked online and some of the remedies I've seen via Youtube look sketchy.