One of the best products for cleaning LCD screens also helps to 'fill in' minor imperfections, at least temporarily is one designed specifically for Plexiglas/polycarbonates used in motorcycle helmets, motorcycle windshields and aircraft windows... Plexus. Clean with a soft cloth or microfibre brush to remove dirt, vigorously shake the can and spray a light coating, top to bottom. Wipe with a soft, lint free cloth (a Vileda cloth is perfect) in a circular polishing motion. I have maintained an NEC screen this way for years and it looks brand new. The Plexus is designed to fill in minor imperfections and though it must be renewed periodically will clean a dirty screen and make an old screen look new.