I love second-hand bookshops, but you can see the death spiral. The neighborhood in which I live used to have about 7 bookshops; they are down to about 3.5 and some of the remaining ones look none too healthy.
One problem with a lot of 2nd hand bookstores is that they have stuffed their shelves with remainders - these are not a interesting stock choice as they are really just "what was selling - or more likely not selling - on mainstream shelves a few months ago". They can't compete on price moving those remainders compared to "Downtown Book Barn" places, and it crowds out genuine used stock (which will provide more surprises).
One problem with a lot of 2nd hand bookstores is that they have stuffed their shelves with remainders - these are not a interesting stock choice as they are really just "what was selling - or more likely not selling - on mainstream shelves a few months ago". They can't compete on price moving those remainders compared to "Downtown Book Barn" places, and it crowds out genuine used stock (which will provide more surprises).