I love your faith in the native common sense of newbies!
It is of course largely myth, and as we see so often,(too often), first they buy on ebay and then they join this board to find out what they have bought. SIGH........
However, to the point of this.... The nature of collecting is surely bound to change in the light of the proliferation of unreliable items and unmitigated faking and profiteering on the part of some dealers. I envision that change to drive communities such as the NMB closer together, closing ranks as it were against an increasingly hostile supply environment.
The great value of places such as this is that even the experienced collector can ask for guidance/clarification from his fellows without fear of bias or vested interest. Thus, as a group, the collectors and students of nihonto become stronger and better informed. Some dealers who offer only reliable items will of course benefit from this and be patronised whilst other less reliable or less scrupulous dealers will be left on the outer.
This bodes ill for the newbie in that alone and uninformed, the newbie is the natural prey of dubious dealers and sellers. This is so now, and will be moreso in the future.
To quote a line from 'The Magnificent Seven', "If he did not want them shorn, God would not have made them sheep!" Is this the new catch cry for the up and coming dealers who have more greed than conscience?