I have an absolute treasure trove of saddles; it's hard to state just how personal they are to each person's physiology. What works for one may not work for another. It can be a long frustrating (and expensive) experience.
Isn't it also like chairs, beds, pillows, glasses' frames, bras, mice, etc. though? You can often tell when it's terrible but not when it's going to still feel good after the first 8 hours of continuous use
Edit: further down the thread someone (https://news.ycombinator.com/item?id=40492169) mentions saddle trials as a potential option, so I guess that confirms it. A saddle library sounds like a good starting point for selecting which one to trial, though!
I think these are just different terminology for the same thing. You take the saddle from the library for a week or whatever -- it's not just sitting on it once in a shop.
