Data on compact discs, be the disc a CD, DVD, or Blu-ray are binary in nature. Unfortunately, the quality of a compact disc is not binary in the sense of working and not working.  A lot of badly replicated discs are in between these two quality extremes, i.e. they work sometimes and do not work sometimes, they work on certain disc players and do not work on other players.  How do you assess whether a compact disc is good or bad?

Common sense tells you that the printing side of a disc has nothing to do with playability.  It’s the silver data side that the disc is being read. The information is read from the reflection of the laser beam. When the reflected ray is weak then the data might be skipped rendering the disc unreadable.  Poorly fabricated stamper and the inconsistent sputtering process will give rise to sputtering smear.  A perfect disc should look as smoothly shiny as a mirror.  When the silver side becomes smeary as a carnival mirror then there is a big quality problem. Never buy the argument that the smear won’t affect the readability.  It will, especially on older CD or DVD players.