What should I do with a DIY book where the people who wrote it did not know what they were tailing about?
I don't even know why you need to start a thread and ask. What's wrong with chucking it into the paper recycle, mulching it etc, whatever.
Sell it to a friend. Tell them that it's the best damn book you've ever read. Yeah, you'll lose a friend, but you'll gain back your purchase price. You have to think of your priorities here. You know, if you know what you're doing, you can make even quality, smooth paper work as toilet paper. I just bought a book that tells how. It's the best damn book I've ever read! Wanna buy it?
I cannot agree with you on this one. There are good and bad. I generally don't buy Readers Digest books except when it comes to DIY books as these as quite well explained with an emphasis on improvisation and not assuming you have unlimited funds. Getting back to the original op if I were to give the book away, I could be misleading to whoever else got hold of it. I have no objection to people expressing opinions that I disagree with, in fact I consider absolute consensus to be potentially a dangerous thing, but I loathe disinformation.