The textbook thing depends on who wrote the book and when. Textbooks change somewhat but a lot of the old mistakes continue to be printed. Show me a book on daggers and I'll show you mistakes in it--ANY BOOK!
Here is an example of how the "textbook" collector hurts the hobby. Collector "T" collects by dagger type and by TM. He is offered a very rare one at "retail" price or a little more. There are a couple of things about it that he or SOMEONE-ANYONE considers Non-textbook. Nothing major really-the crossguard does not fit the scabbard PERFECTLY-or the grip may not be exactly the same shape as usually seen. He does not buy it-he is not really experienced but he makes a big ego trip issue of it on the good 'ol internet. Result-no one will buy it-a rare item becomes a non-collectible lost to the hobby. New collectors see this and begin to question every item they have-and they will almost always find some little something that is not 100% textbook. They consider and conclude-this ain't worth the worry.-they quit the hobby. One more lost who might someday buy YOUR stuff. "I have seen the enemy and it is us" POGO.

MAX & OVMS Life Member, MAX Bd. of Experts. GDC Platinum Dealer. Collector since 1955.