I recently purchased a CD from a online retailer that had several tracts that would not play correctly or not play at all. I copied this CD to CD-R. The copy sounds fine, at least to my ears. I also had an older CD that somehow got "scratched" and had several tracts that would not play correctly. I copied it and obtained the same results as the first.
How is this possible..? Is there a fairly simple explanation that a non-audio engineer might understand?