There's a lot of good info in this article, but there's also a lot more beyond it. For example, it mentions (accurately) that the fineness of cotton and wool fibers is an indicator of its quality, but the fiber length is a greater indicator of quality. Unfortunately, cotton and wool products are frequently marketed according to their fiber diameters (e.g., "800 thread count bed sheets" and "Super 100s" wools for suits), but you will never see the fiber length listed. You need to either be able to feel the fabric to assess its fiber length (something that I was never really able to do well) or rely on the recommendation of someone else who can. It's like saying that a network link has 10Gb bandwidth but failing to mention its 100ms minimum latency.
Another item that they mention that is frequently misunderstood is that there are different types of fabrics, especially wools. Just because a specific type of wool such as merino is mentioned doesn't mean that it's good quality. There is both junk merino and excellent merino. Just because it came from a merino sheep doesn't mean it's great. The same goes for cashmere, alapaca, angora, mohair, camel, etc. It's like saying that it's an SSD rather than a 7200rpm HDD. The former is almost certainly better, but there are still a wide range of SSD characteristics to be evaluated.
Yet another item is that while it is true that expensive clothes are not necessarily high quality clothes, it is almost always the case that high quality clothes are expensive. Or rather, they're expensive upfront but often turn out to be more economical over the life of the garment. In either case, they will be more pleasant to wear than a lower quality alternative.
And the Last item, since I could go on indefinitely about this, is that garment quality should be assessed on three axes -- quality of materials, quality of construction, and fit. If the first is lacking, the garment's material will pill, rip, fray, or just plain wear out too fast. If the second if lacking, it will fall apart too soon. If the last is lacking, it will be uncomfortable and look bad on you. The trick is, of course, to find garments which have all three.