Are you kidding?
I have seen "old IBM keyboard" with no further discussion AND no picture.
When I asked a question, they said that it said "Model M" on the back, and posted the question to the listing. Obviously somebody else saw the question and answer, and topped my bid of $5-10 and won it at that price.
A photo of the front would have at least doubled the bid, and a photo of the back might well have tripled it.