I discovered rain-x in 1991 while living in NYC where rain, sleet, snow rule during winters.  Back then, I had purchased my first new car and decided to try rain-x after seeing a promotional display (convinced by the marketing claims imprinted on the box).  After the first application, there was a hazy glaze on the windshield and other glass surfaces I had applied rain-x on.  The haze dissapeared after turning the windshield wipers on for a couple of minutes.