GREENSBORO, N.C. — You might have seen life hacks online that say you can clean off your headlights with bug spray or toothpaste. But do they actually work? We did the experiment for you. We used OFF!

Among the 35 (technically 34) non-tooth-related uses the Coupon Sherpa suggests for toothpaste, two of them are of particular help to anyone who's been nagged by the small scratches that accumulate on ...