This is sadly something employees have to deal with every day. I don't work at the store in question, but my store has simular expreiences every day. The key you have here is 3/4 former best seller in hardback. Condition at this point means very little. At my store those books would go out for $1-$2, sit on the shelf for 3-5 days then be donated to a local charity. For the 35-40 you brought us, maybe 2 or 3 would sell. Any that we would put out on the main shelf would go out at 5$, and displace the copy that's almost certainly already there, making it go through the 3-5 day $1-$2 cycle.
Art/photography books are an ugly beast, we look them up and go by the used price online. Given the low amount offered you, I would have to guess that most of them looked up online (amazon and other online reseller websites) for less than 5 dollars each. This is true for most non-fiction books, especially those that go out of date quickly, like law, medical, and psychology, or that lose popularity quickly when society stops taking an interest in the person/subject, ususally art and tv/movie actor/actress books.