The problem with blaming the purchaser is that even if 20 experts turn a specific one down, someone down the line WILL still pick it up eventually.
The gun does not vanish into the Ether, never to be seen again, it is presented as a working piece by the vendor, until it's rung up, out the door, and all problems fall upon the relationship between the Manufacturer and the Customer.
So, somehow, it's incumbent on the prospective BUYER to
overlook problems with a gun?
I wonder how well you take your own advice?
It doesn't take an "expert", no matter what you, personally, think, to see that there is very little barrel-cylinder gap, or that a forcing cone is wrong, a barrel canted, or a finish problem.
The shop is being unethical when, after a person points out an obvious flaw, they continue to present the piece as working and flawless. It can be returned to the vendor, or distributor, for credit, as they mandate that what they have provided the shop is a functioning product, without flaw.
IF
you believe that gun stores are
all doing this, it certainly makes sense for prospective buyers to check all the more thoroughly anything that they might want to purchase.
I find excusing common sense and business ethics distasteful, dishonest, and downright simple-minded.