They do deteriorate. It also applies to regular CDs as well as the recordable CDs. It is my understanding that deterioration is primarily due to poor quality construction of the CD itself. Some will last longer than others depending upon how well it was made and what materials were used. If you search the archives, you'll find some previous threads on this topic.
How long will CD-R's & DVD-R's last?
Several days ago a thread was posted, in which the discussion was about how to copy tapes to cd. One of the responders, in a passing comment, mentioned that cd-r's would only last 10 years. This got me to wondering, is this scientific fact, or "audio wives's tales"? I'd be interested to hear about the longevity of recordable media from folks who are in the know on this subject.