This is a book by a professional debunker; a man who does the circuits deflating people like Holocaust deniers. This book attempts to explain the difference between science and pseudo-science, in which people with a variety of (usually non-rational) claims attempt to make their theories sound like science by adopting the dressings of science.
I had to stop, part way through, because its tone was a little too smug, too self-congratulatory. True, the author pits himself against some real nuts (Ayn Rand, Ernst Zundle), but his writing style defeats him by becoming a touch too didactic and ranting. He sounds like the zealots he's trying to explain away.