At a songwriters convention in LA, one of the speakers addressed this topic.
Don't use the stick on labels, was the advice he gave.
1. They do not look professional.
2. Depending on the label's paper, they can flake and cause dust inside the CD drive... not good.
3. The labels (some kinds with metallic backing) can affect the reflective nature of the disk.
4. The label glue can give out allowing the label to come off.
5. The label can wrinkle up due to moisture/heat and that makes the disk unplayable.
6. The label, if not installed properly and perfectly, can cause the disk to be out of balance.
The other advice was to use the printable CD's, making sure they are AUDIO and not data disks. Data disks will play on some CD players (usually computer based) but may fail to play on the commercial players in many stereo systems.