Ah I am reminded of buying as "previously viewed" Disney DVD from Blockbuster Video. I always checked those disc for scratches and fingerprint etc - when I realized the play side was covered with dried on gunk - which I determined was actually caked on peanut butter and grape jelly!. I had to...
I've put plugged my Sony X800 into a switchable outlet strip to save wear & tear on the plug. (The outlet is plugged into battery-backup/UPS) Sometimes cleaning the disc will help with playback and usually I can continue on with the show ....