I don't intentionally ride in the rain, that's for sure! I do get caught in the occasional drizzle...but I've always kept my helmet and visor waxed, which helps shed water. Recently I've switched to using the new spray on ceramic waxes (turtle Wax and Griots garage both have excellent ones) on my helmet/visor (and bike, scoot and cars, too, amazing gloss/durability and easier than ever to use).
A slight turn of the head and poof, the water's gone!
But it would also be nice if your bike or scoot had a built in face shield drier like Neil's!