It is very difficult to quantify and measure quality, not the least of the problems is that we don't have a good definition of quality. However, like porn, we know quality when we see it. And we like to see a lot of it.
Kwalitee are measurable traits usually associated with quality code. For example, quality CPAN modules tend to have POD and tests. Their distributions have README and Changes files. They use strict.
Kwalitee recognizes that measuring quality is very difficult, so it measures what we can measure and hopes for the best. Kwalitee is like measuring lung cancer by the number of ashtrays in a home. Ashtrays don't cause cancer, but if they're around there's a good chance someone's smoking. And its a lot easier to count dirty ashtrays then give your neighbors chest x-rays.
But be careful not to think there is a cause/effect relationship between kwalitee and quality. Red cars tend to be fast, but your car will not go faster if you paint it red.
Once upon a time when Schwern was a freshman at CMU he lived in the Doherty Apartments. A pizza was ordered. When it arrived, the box was labeled "Doritee". This sort of mispelling quickly became used for anything slipshod. Thus, "Kwalitee".