If it really is a dirty glass and not a scratched glass, then tire bleach and ultra fine steel wool will clean the glass just about as clean as you're going to get it. This is a very effective way to get dried bugs off. The Mr Clean pads might work, too. I use them some, but the steel wool and tire bleach works so well that I haven't tried the Mr. Clean pads on the glass. I use the steel wool and tire bleach on chrome tips with the same results.