I have copies of the same CD, one manufactured in the U.S. And the other in U.K. and the latter version sounds better. There are some CD manufacturing facilities that have higher quality control than others, same A's LP manufacturers.
How vinyl records are made
Here are a couple of really cool videos on the record making process. I can sure understand how records can have defects in them. There are alot of different steps involved with the potential of messing things up!
http://www.enjoythemusic.com/magazine/manufacture/0809/how_vinyl_records_are_made.htm
http://www.enjoythemusic.com/magazine/manufacture/0809/how_vinyl_records_are_made.htm