It all depends. I've read/played some pretty scratched up, messed up, dvd's and cd's. I even have a movie at home that the kids had put three of four pretty deep scratches in. I used a soft cloth and cleaner, and then copied it using DVDSHRINK and DVDCRYPTER, on my Plextor PX 716. There are no noticable problems with the copied movie, and the original also still plays fine. But it all comes down to how bad the scratches are, where they are, and the quality of your reader and how it handles error correction. I've also had some cd's that were so messed up that my LiteOn wouldn't even recognize them, and used a CDSHARK to clean it, and it worked fine.