How sensitive to the disc's surface cleanliness is playback, compared to CDs & DVDs? Some of my laserdiscs play back with various specks (not actual rot). I know that's common for laserdisc, but was wondering if that's something that can be improved by cleaning the disc. My discs mostly look fine, but aren't cleaned to a shine. I'm always afraid of marking up the surface by trying to clean it, so I've always just played them as they are. But I'm starting to transfer some to digital now and wonder if a cleaning is in order.