While I agree that being skeptical about self-help books is a good thing, I think you made a big mistake in your specific example. I have not looked at "The Feeling Good Handbook" that you linked to, but I am quite familiar its predecessor (by the same author), "Feeling Good", which is excellent. It has helped a couple of my friends, and at least one other HN reader.[1] Further, its efficacy is supported by at least one clinical study.[2]

You're right about the image, but the book is worthwhile.

[1] http://news.ycombinator.com/item?id=4509281

[2] http://www.ncbi.nlm.nih.gov/pubmed/2738212 (The book is not cited in the abstract, unfortunately, but I believe this is the correct study.)