I think most golfers, and even many people on this site, see a routing as just another attribute that can either enhance or detract from the quality of a course, while in fact it encompasses a hell of a lot more than that. In my opinion the best way to judge the quality of a routing is to simply judge the quality of the course! If it is a good course then it must be a good routing, and if it is a bad course then it must be a bad routing. There is no doubt in my mind that the quality of a routing is directly proportional to the quality of the course.
Obviously, though, to understand how the architect was able to create a good routing, one most know the property more intimately than simply that which he knows through the playing corridors and the order in which he plays them. When attempting to explain why a particular routing is good, many golfers offer reasons such as "short green to tee walks," "the holes flowed together nicely," and "both nines returned within steps of the clubhouse." These are reasons that can be applied to any course on any piece of property, while in reality the reasons for why a routing is good lie in the ways an architect uses specific features to create interesting holes. This is why the golfer has to know things like where specific holes are in relation to other holes, and the features of a site to appreciate a routing. I have worked on a couple of different maintenance crews over to past couple years, and I have found this to be a very good way to be able to truly analyze a routing. I currently work at Milwaukee CC, because I had heard many say it was a great routing and I wanted to figure out why. Through being able to study how Alison used features such as the ridge that runs between 9 and 10, and along 1, and the Milwaukee River, I have been able to better understand what constitutes a good routing. When asked why MCC has a good routing, many people have responded with evidence such as the fact that both tees heading out, and both returning greens are within steps of the clubhouse, and Alison's decision to move the clubhouse off the high point of the property so that his 18th fairway could lie there. To me though, these are only very minor aspects as to why MCC has a great routing. Instead. I would offer the opinion that the greatness of MCC's routing lies in reasons such as the way Alison used a ridge to offer both 1 and 10 with rousing tee shots, used a small rise in the ground to cut bunkers on both 5 and 6 into, used the ridge to create a exceptional greensite benched into the hillside on 10, used the River and a elevated tee to create a aesthetically enchanting tee shot on 11 while also creating one of the most interesting greensites I have had the pleasure to experience. To me, holes such as these are the essence of great golf course architecture, as they blend both the impalpable pleasures received by a beauty detected by the senses, and the rational pleasures received by the use of our mind. There are few, maybe none, greater joys than to be in the presence of a truly remarkable landscape while simultaneously being presented with an interesting and pleasant task. The better the architect can offer this, by blending the two pleasures, the better the routing, and the course, will be. So then, one cannot simply analyze a routing by simply looking at the course from a broad viewpoint, but rather has to analyze the individual qualities of the holes. I think this is where many people go wrong, because they look at routing as simply the sequencing of holes. I'm no expert, but I honestly think that a good routing has very little to do with the "flow" of holes. Instead, it has very much to do with the individual qualities of holes, because had it been a bad routing many of these qualities would not exist.
So, in conclusion I think the best way to judge a routing is to simply judge how good the course, and the individual holes are in relation to the property, but to understand how a architect was able to create this routing one has to enter into a much more in depth analysis of the property and how it relates to the qualities and sequencing of the golf holes.