DVD players can scratch discs, sure. If there's foreign matter inside protruding or blocking (you'd be surprised what has ended up inside players, if you have kids), or if the player is vibrating because of a disc not being 100% flat or having an uneven label.
Moving the player with a spinning disc inside could result in circular scratches (happens a lot on the 360). Straight scratches usually happens while the tray is being closed/openened.
A funny story btw, a friend of mine who is using his 360 as a DVD player, was suddenly getting lots of scratched discs. I went to his place to take a look. Turned out his 360 was right next to his new earthshaking 15" subwoofer.
Last edited by crs; 05-06-08 at 12:00 PM.