I think everyone who has any role in the design of user interaction environments, no matter how peripheral or glancing (and yes – book displays and public service desks count!) should read this article.
Manipulation and Design by Jon Kolko (posted by UX Mag, July 23, 2013 – Article No. 1059)
His critiques are spot-on and his conclusion is important. Such considerations may seem overwrought in the context of public service desk or book display design, but the ethical responsibility to help is appropriate for all—and especially for libraries.