My old Plextor 712 is also a very good reader. The NEC 3500 won't read a badly scratched DVDs.
Putting label on CD/DVD is a no no. The warning label on most media said not to attach anything on the CD/DVD. The label will "unbalance" the disc, causing excessive flutter of the reading surface when the disc is spinning.
Use a felt-tipped permanent marker to label your discs.