I'm going to try a different angle to address your question. As others have posted, the quality score isn't that good of an indicator. A search will turn up comments that it's based solely on the peak of PIF, and while I think that's true, I'm not sure how Nero comes up with it.
It may be more useful to note how many PIF's are occuring, and what the maximum is. The QS can drop very low on a single peak of PIF, even when the total PIF count is quite low (say 200), yet give a high score on a disk that has a max of 2 PIF, with a total count exceeding 1500.
Eventually you'll find a TY that scans with a QS of 98 or 99, but it's rare. Instead, look at the flatness of the scan. How much of a climb is seen at the tail, what is the peak, and is the PIF chart dense or sparse.
A sparse PIF chart is a good thing, a flat PIE chart is good, even if the count is fairly high. Only one POF and you've lost data for sure. Zero POF, and no matter what the other charts show, the data can be read on that burner at that time.
The most use you can get out of the scan is a general quality control review, not a literal assessment of the disk itself. What I mean by that is, you can see how predictable and stable the drive's performance is, and the media quality is, from disc to disc. As long as this doesn't drift wildly out of norm (and norm is simply what your system is generally reading from a particular media), then your system (from drive through software) is stable, and the media is stable from one disc to another.
Scans are going to alert you when a problem is developing in the drive, or the media varies wildly.
To improve your score, make sure you're not starving the drive (so it doesn't go into seamless link mode - though frankly I've done it and the scans are still good), keep the media covered, don't let the cats warm up by the CPU, and make sure the TY is genuine TY.
Oh - special note I might post elsewhere - stay off your cell phone.
The transmission signal of some cell phones can actually interfere with some circuitry! Want to see it happen? This worked for me: dial someone, and place the antennae near the speaker of a cheap phone answering machine or clock radio. Even with the device UNPLUGGED AND OFF - there's enough juice to make the speaker click loudly.