Most nonfiction books are not fact checked; if they are, it is at the author’s expense. Publishers have said for years that it would be cost-prohibitive for them to provide fact checking for every nonfiction book; they tend to speak publicly about a book’s facts only if a book includes errors that lead to a public scandal and threaten their bottom line. Recent controversies over books containing factual errors by Jill Abramson, Naomi Wolf, and, further back, James Frey, come to mind. – Esquire