According to some claims, bug spray can be used as a headlight cleaning solution in a pinch thanks to its chemical composition. The primary ingredient in most commercial bug sprays like OFF is diethyltoluamide, better known by its shorthand moniker of “DEET.” When used in small amounts, DEET is a natural bug repellant. Note that we say “small amounts” there, because in larger quantities, DEET can swiftly become corrosive to certain materials.
While DEET isn’t harmful to human skin, it’s naturally opposed to certain artificial materials like plastics. When a large quantity of DEET is applied to a plastic object, the chemical will melt the object’s outer surface, reducing its overall structural integrity and leading to further damage down the line.
Using a DEET-powered bug spray on your headlights won’t clean them (even if it looks clearer at first), it’ll irrevocably damage the exterior shielding. That can make headlights more susceptible to damage, or the elements could seep into the lamps themselves and do more damage.
