These are the music CDs that:
"1. Prevent you from copying it for personal use or from playing it on computerized devices (computers, DVD players, game consoles, MP3 players, consumer CD duplicators, car CD players and more)."
"2. In the United States, these 'copy-protected' CDs are often unmarked. Once you buy it, you can only exchange it and hope that the replacement isn't defective too."
Click on either the link in the Headline (above) or the link below for a list of some of the known bad CDs here in the United States.
http://www.fatchuck.com/z3.html
From Fat Chuck's website: "Return Defective CDs Every Time. You'd be surprised how often people don't return CDs that are defective because they think it's their fault. If you get a defective or corrupt CD, please return it for a good exchange or a refund."
Edit: Apparently the EFF has released an incomplete list of Sony/BMG CDs which have the root install DRM on them. The page also shows where to look for the labels, which it seems you can only see after purchase. I thought coming accross this link was worth updating.
