Sorry, I guess I ranted for a while...don't feel you need to go into such great detail...
The worst chess book I've ever read, and why...

I don't have one particular "worst" book but anything by Gufeld is junk. Since it is winter, pert near, above the equater, you can use his pulp to start a fire ;-)
I have this book and I agree it is mostly garbage from an author whose other works are commendable. I suppose we all have off days.
Without Fred Reinfeld, someone ELSE would have to be called the worst chess writer ever. Way to go, Fred.
His later books were bad when he was just going for output but some of his earlier ones were excellent eg A Treasury Of British Chess Masterpieces 1950 and British Chess Masters 1947 and Tarrasch's Best Games of Chess.

Seven Deadly Chess Sins By Jonathan Rowson.
This book focusses on making mistakes. If you want to laugh,...read it. If you want to win more games, give free copies to your opponents.

His best works included "Aron Nimzowitsch: A Reappraisal"
How does Keene's work compare with Watson's more recent reappraisal of Nimzowitsch?
Btw, I don't agree that Reinfeld is the worst author. He wrote some really good stuff like "The Immortal Games of Capablanca", "Winning Chess" (with Chernev; such a classic that I have bought a used copy, even though it's DN and there are newer books on tactics) and "1001 Chess Sacrifices".
I've never liked most of what I've read of Pandolfini.
I never liked "Bobby Fischer Teaches Chess." It is a simplistic book ghost-written to exploit Bobby Fischer's 1972 world championship triumph, obviously without any participation by Fischer except the use of his name.
But for really bad, try out "The Grand Tactics of Chess" (1897) by Franklin K. Young, where he explores in detail such strategic concepts as the "Oblique Right" and the "Crochet."
Although the Young book is not the worst I've ever read: I didn't read it. It's just the worst I ever heard of.

The good news for me is that I don't think any of my chess books are bad out of like 15, probably because I look them up most of the time, but that's a smart thing to do.

Dang, but it's hard to say which of E. Schiller's 100+ books is the worst ever.
Why are his books bad? Maybe he's trying to make money by making so many of them, but from the few I looked at they don't seem that bad. He seems to explain the ideas and pawn structures in a decent way.

There's nothing to read in Wall's books. No words. Just stupid algebraic notation and a few diagrams. And its even worse if one of your chess losses shows up in one of his books. That's the worst. Not ready to burn, though. Florida weather in the 80s. And too rough for toilet paper. Could be used as a trap.
Okay, somebody posted a thread asking to reccommend chess books for him, and so I did. But, that got me thinking about the other side of the coin. What's the worst chess book you've ever read?
I'll tell you what mine was:
"How to Think Ahead in Chess"
...by Horowitz and Reinfeld. This book was a complete piece of junk. The book taught you as white to play ONLY the stonewall attack (and never mentioned the possibility of black playing a g6 defense of any sort!). As black, you played a single variation of the Sicilian againt e4 and the lasker defense of the queens gambit declined against d4. That's it. That's the entire book. It was so limited in scope that to follow it's advice would have no benefit to anyone rated above, probably 1200. It's approach as black was poor, particularly as it was reccomending the Dragon againt e4 (without mentioning the Yugoslav attack!!). Maybe the book was first written b4 that attack hit in the late 50's, but my edition was from 1973(!!!) and there was no mention of it.
But really the worst of it was that it gave no clue as to how to approach the game as white if black didn't fall into the extrememly passive setup that the book showed as blacks only option againt the stonewall. Really pathetic.