CDs that have derogatory and offensive lyrics should always be labeled. Parents who are buying the CDs for their children have a right to know. Some people do not want to listen to music with offensive lyrics and they have a right to know what words are going to be said on the CD.
Yes, CDs with offensive lyrics should be labeled. This is because many parents do not want their children to be exposed to those sorts of things. If they are not labeled, consumers can not make a wise choice. Labeling the CD allows the consumer to decide if this is appopriate listening material for themselves or their children.