Had helmets with visors previously and a microfiber cloth was normally good enough to get any sweat or rain off and get it smear free.
New met helmet is proving much more stubborn.
Microfiber didn’t touch it.
Glasses lenses wipe also less than effective.
Good old damp cloth cleaned it… Then left its own smearing when it dried.
Apparently it’s got a film on the inside… dunno if that’s true.
Don’t want to trash it with anything to aggressive. Goggle spray? Anything else people use?