I know this is an old post but I thought I would add something to it. I seen a post on cleaning the yellow off of headlights with Deep Woods off and a towel. I tried this with a small spray bottle and an old sock. It actually works. Mine were not a dark yellow as others maybe but there was a difference.
This is what it looked like before
and after
I did take some water to wipe off the bug spray but it worked pretty well!!