I don't have a problem keeping the outside of the windows clean but I get a thin haze film on the inside of the rear window. I'm not sure if it's caused by the vents blowing (that's what I am thinking) but not sure. It's just a real pain to get back there and try to clean them and when I do I seem to always miss some spots and I only notice it when I'm driving and the sun blares down on the rear window. And that happen a great deal in San Diego, CA. Does anyone know what causes that haze?