Early on (a few years ago) I had a lot of success buffing headlights out with either 3M or Meguiars Plastx. Both are great products and with an Orange cutting pad and the Porter cable it was a 5 minute job. Some of the ones I've seen lately though are a lot worse and the technique I mention above does not get the haze/fog out. Those that are pitted and heavily hazed need the kits with the sandpaper to get them back to good condition. Meguiars makes one, there are other headlight restoration kits out there as well, I think Adams makes one too. My only other suggestion here is that you make sure the plastic is hazed and its not condensation, that's a whole other issue.