One of my favorite things about the Book of Mormon is its pragmatic view of human nature. Undoubtedly, its authors knew the best and worst of the human experience, and weren’t pulling any punches.
An example of this is the honest depiction of missionary work here, namely its tediously frustrating reality. Though the Book of Mormon does have some more neutral general observations about how people are (such as here and here), most of the time the text is pessimistic.
Here are nine such passages:
O that cunning plan of the evil one! O the vainness, and the frailties, and the foolishness of men! When they are learned they think they are wise, and they hearken not unto the counsel of God, for they set it aside, supposing they know of themselves, wherefore, their wisdom is foolishness and it profiteth them not. And they shall perish.