Toothpaste, WD40, brake clean..... they all can clean up lenses, but will also damage the plastic. I used 3m cleaner on mine; worked great, then I did them again, and they got hazier and hazier. I gave up and got new housings for $72. They were 10x better than the 3m cleaner.

Old/cleaned housing on the left, new TYC housing on the right:




And these are my latest.....retrofits a-la-Classy. The only way to go!