She used regular Crest toothpaste (not the gel kind) and spread it over the headlight with a cloth and scrubbed it into the plastic really well. Then she washed it off and you could see a difference just doing it one time (she ended up doing it a few times after she snapped this photo.)
The arrow shows the line between the clean and dirty side.
She was pretty tickled something so simple could help clear up some of the fogginess. After all, we DO have a stash of toothpaste thanks to all our CVS deals! 😄
Another view of clean on the left, dirty on the right.