I spent an hour literally digging through their collection. The most amazing thing I found was a "window" that was cut into a shelf! I can't post the picture because of copyright, but really, check it out! They seem to have glued large books in place to hold the shelves, as well as the sliced books. I stood an marveled for a good five minutes!
Unfortunately, they didn't have the two books I was looking for. One was Euclid's Elements, or some version of it. I was in the math section, on my way back downstairs, when I passed a room labeled "Travel". The shelves inside looked interesting, so I took a step forward. Suddenly, out of the corner of my eye, a mouse scurried across the floor and dived into a pile of books.
I have to say that did it for me. It's true that Doull has an amazing selection, and I know they are trying to go for the disaster-yet-organized look, but cleanliness has its values. I may go back if the need comes, but I will be sure to stomp very loudly before I peek into a room!
Picture of JWD Booksellers by Miss A, http://www.flickr.com/photos/miss_a/9994353/