Use that little patch of felt or whatever it is that's on your glove thumb to wipe the lenses once in a while. Make sure you don't use the side you wipe your nose with.
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(Life is too short to play crappy guitars) 2006 Raleigh Cadent 3.0, 1977 Schwinn Volare, 2010 Windsor tourist. ( I didn't fall , I attacked the floor)