after he switched his headlights? what kind of headlights?

cheap aftermarket lenses will do that sometimes, or if you open them up and don't re-seal them very well. it happens because they're not sealed properly and allows moisture to get in and fog up the inside of the lenses. he has to dry the inside first, then use silicone sealant to apply a better seal. he doesn't have to take them apart, just run a bead of silicone around the seal and hope it works. drying the inside is kind of tough. if the weather is dry and warm they might dry on their own. my corner lenses are like that; they're pretty much dry all during spring and summer when it isn't raining. in fall and winter they start fogging up again.. otherwise he'll have to figure something else out. maybe taking them off and putting them in an oven at low heat for a while would do it? gotta be careful not to melt or warp anything :dunno: