These are quotes by Andy McFadden from his cdr faq website.
I've referenced often, especially about this topic..LABELS...
The adhesives on some labels can dissolve the protective lacquer coating if the adhesive is based on a solvent that the lacquer is susceptible to. Asymmetric labels can throw the disc out of balance, causing read problems, and labels not designed for CDs might bubble or peel off when subjected to long periods of heat inside a CD drive.
Adding an adhesive label to a disc can make it look more "professional", but you have to be a little careful. If the label and the disc aren't a good match, the label can start to delaminate after a while.
It may not be a good idea to put labels on discs that will be fed into a "slot in" CD player, such as those popular in dashboard car CD players. Sometimes the added thickness will cause the disc to get stuck.