Another topic that comes to mind is parenting. I'm not familiar with the self-help literature in this area, but there are some quite ugly truths which I'd bet these books don't say, for example how depressingly little you can do beyond the limits imposed by heredity. Moreover, fully accurate no-nonsense advice about what you can do to maximize your kids' expected success in life and happiness would require a cynical analysis of many respectable social institutions, customs, and beliefs, to the point where it would probably be too offensive for mainstream sensibilities.

Less than two years later, Yvain is doing pretty much that on his blog.