I use plastic auto lens cleaner on all plastic that I want to stay clear. They sell in kits, usually an attachment for a drill, a sponge thing you put the liquid on and then use your drill. I can polish anything plastic with this and have. The success rate will depend on how soft the plastic is(the softer, the better) and the amount of TIME you want to spend on the plastic. I once spent over two hrs solid, polishing out some plastic headlight lenses. They were HARD plastic, but I won the battle.
Back in the day, a lot of guys just used toothpaste as a plastic polish....this stuff is high tech and works wonderfully without fluoride...lol.
Kevin