This sounded like the practice of some people to order 3 copies of the same lens, test them to find the best, and return the other two.
Then your ears are bad. (Or your interpretation of what was written

)
My purchases were nothing like this.
Ethical? I do not know.
I would call your example unethical (or "shady") on the part of the buyer.
The trigger of legitimacy versus fraud is intent.
A buyer of 3 of the same lenses, who
intends to send 2 back, is fully-aware that 2 of 3 transactions are
not legitimate purchase efforts.
I did no such thing. I made a legitimate purchase effort, was not satisfied, and returned the lens in accordance with the intent of B&H's return policy.
I selected another lens, different brand, same range, in another legitimate purchase effort, was again not fully-satisfied, and returned that lens as well.
I then purchased a 3rd lens, again totally different but same range (which was more expensive than the other 2 put together).
I kept the last and most expensive lens, because it performs
beyond (not below) my expectations, and I am 100% satisified with it.
(The truth is, I would have preferred to spend less, wasted less time/effort, and have kept my first choice; but that's not the way it worked out.)
Therefore, the difference in
intent in the two examples is night and day.
But I do know that when I order a new lens or camera, I expect a virgin new, untouched. Otherwise I'd buy used.
Then your argument should be with B&H's allowance of a return policy, not on the return decisions I made in exercising my right to use that policy in
exactly the manner in which it was intended.
Jack
PS: For that matter, it could also be argued that, if B&H allows people to "Buy 3, send back 2," then even that purchaser is within his rights. So, even here, your argument would have to be with B&H's policy (or with whatever salesman is allowing people to "bend" B&H's honorable policy into something not intended) by allowing such antics.