Life has always had its hucksters, it just takes a different form and if you don't know what you are doing, don't play in the arena.
My first ROA was sold by a guy who did not know anything about them, but he was knowledgeable enough about guns to say he thought it was gunfired but would not guarantee it, more than fair. Obviously not his mainstay and why should it be? A lot of people wind up with guns they know nothing about.
The ones I laugh at are the ROA sellers who want $1000 for one and it never sells, they just keep relisting it.
I saw a fake bayonet go on Ebay for $400. Rare type all right but wrong grips. I only know that because I got one out of a grab bin when I was a kid!
Educate yourself, figure out what you want to pay for it and take it from there.