Pedigree is only a probability, not a guarantee. It is true that a horse’s ancestry actually affects the chances of it having a certain type, a particular way of moving, and a specific temperament, and this kind of information is used every day by experienced breeders. However, pedigree cannot tell you if this particular horse is sound or whether it will be suitable for your riding, and it is up to you to check these things yourself.
How much the papers should matter depends entirely on what you are buying. For a foal or a very young horse that has proven nothing yet, the pedigree is most of the evidence you have, so it carries real weight. For a trained horse with its own competition record, the horse has already shown you what the breeding only hinted at, and the papers matter much less. Paying a big premium for a fashionable name on a horse that has already proven itself is paying twice for the same information.
Well-known stallion names appear in advertisements, and with some of them there are good reputations. There are certain lines which are famed for producing sensitive and hot horses, while others are promoted because of their easy-to-train temperaments. You should regard these reputations as a guide to the things you should look for when viewing the horse, not as a judgment about the one in front of you. Each line brings forth both outstanding examples and disappointments.
There is one habit that is actually very useful and which requires no cost at all—it consists in checking the documents against the horse and the official records. Since Europe’s studbooks and the competition databases used in the sport are open to the public, it is possible to verify an advertised competition record or a grading title online in just a few minutes before you even leave for the airport. When you see the horse, scan its microchip and then compare it with the passport. Putting the paperwork with the wrong horse is one of the oldest scams in the business, and a cheap chip reader makes it impossible. When looking at a pedigree you are not there to admire the names; what you should do is make sure that they belong to the animal you plan to buy.