Talkign about the Gosnale "skin" verses "pattern" that is. You forget to mention "color", often included under "quality". Depth of color in Gosanke is VERY important, 3 coats of paint verses 1 coat as an example. Then when you start drawing comparisons between only 2 elements, are they wieghted equally or not? and then, at what level within a "scale" do each fall and then to wieght them accordingly....becomes mind bogling when approached from a "statistical analysis" methodology. Judges spend countless hours studying traits and putting them together in an attempt to judge the OVERALL IMPRESSION of the Koi verses attempting to approach from an almost impossible task of "grading" based on statistical analysis. That is why you may hear people talk about "training one's eyes". This allows for taking the overall impression based on the given traits and taking a more wholistic approach towards judging.
More "Mud", right?
Now for Shusui, being doitsu, the "paint" is only a single coat and should have Crisp edging and even tone throughout. This will lead to a better overall "impression". The degree to which any attribute may not be perfect is wieghted against each other in that overall impression. Would I prefer even color tone and sharp edges over symetry? Yes, to a point since depending on the degree against "perfect" that its falls away from the standard, will determine the overall "impression".
Even more mud, right?