I find myself in the strange position of agreeing with Boatbums. I have read a number of books that had the Nihil Obstat that left me scratching my head over their orthodoxy.
Also, please note I said as a guideline that's vastly superior to a specific alternative. I prefer to start with the Imprimatur and go from there knowing that there are exceptions as opposed to giving the latest Purpose Driven Bestseller the same status as everything else to be judged by my Self and Self Alone. That's like individual interpretation of Scripture, it almost totally rules out any correcting of what someone already accepts. Just disregard a book you don't know in advance agrees with you, decry any interpretation of Scipture you don't like, or even throw entire books of the Bible out if you feel like it, and go on your merry way.