How many forms of Jitter can you identify?

Just a few days ago I was read about a clock upgrade for a CD player that was said to reduce jitter by having a more accurate clock. Today, I'm reading about a Mikrosmooth CD polishing kit that claims to reduce jitter.

I'm absolutely positive that it isn't possible to apply a product to a CD that will have any effect on the digital clock on the CD player. I'm also skeptical that it can make any difference in how the CD player spins the disk so how does it reduce jitter? At most it should a good cleaning product that could allow the laser to read the disk better eliminating any error correction from being necessary.

What am I missing?