One of the problems with optical drives is dust, dirt, and oily grime is sucked into the optical drives by the case fans pulling from the case interior. The oily grime is the bad stuff as it includes sticky residue from our own dander (dead skin), pets (cats are the worse), hair, kitchen/cooking, cigarette smoke (almost as bad as cats), etc. and that can coat the lens (and everything else), causing the next round of dust to stick to the grime. Those cleaning disks then brush through it, but don't necessarily clean it.
I periodically take my computers outside to blast them out with compressed air and hitting up the opticals is one area I concentrate on. If you don't have an air compressor (that is properly setup for blasting electronics with a suitable moisture and particulate filter), you can try using a can of compressed dusting gas (available at home improvement, computer shops, and even Wal-Mart). Just ensure you keep the can level so only gas, not liquid is spewed out.
Proper storage and handling of the disks themselves helps eliminate grime and dust build up on the disks, and not carried into the drive and onto the lens.