Prepare to have your mind blown.
No, really. I'm a book nerd through and through, but there's always something more for me to learn about books.
Just the other day, I'm listening to a lecture for my Access to Information class (getting my library and information science masters degree swag on) and my professor is talking about how "information" is defined by the patron and what is useful to them, not necessarily what is correct or most up-to-date. The patron decides what materials are helpful to him/her, so the patron determines what materials are ultimately the right information he/she needs.
Then my professor said something that had never occurred to me before. (I'm paraphrasing...)
You see this all the time with nonfiction. If, for example, a patron comes in requesting a book on the Atkin's Diet, our job is to show them to the Atkin's Diet. We can let the patron know that more recent books say that the Atkin's Diet isn't the best thing for weight loss, but it's not our job to lead patrons to those materials when they specifically asked for something else. Nonfiction does not necessarily mean the truth--it simply means that the work is not a narrative fiction story.
To be honest, I'd never considered how works in the nonfiction section might not necessarily be true. I always assumed that the works that some think are true and some think are untrue were conveniently housed in the religion/philosophy section or the politics section something. As it happens these specific sections are usually only found in bookstores--not libraries.
Good to know, huh?