I read so many business books, and they are hard to get rid of after you have amassed a large collection of several hundred. On reflection, many seem like crap, or maybe a good few points what could be summarized in a few pages but somehow turned into a long book.
I'm still glad I read them, and the jewels have always made it worth the adventure.
I really like looking back at the discredited books I've read and in hindsight, asked myself how I was fooled at the time in not detecting the the weaknesses in the books. It has always been a point of reflection to improve these detection skills when reading new material.
For me, at the time of reading, the books: "In Search of Excellence" and "Think and Grow Rich" seemed great, but in hindsight, "What was I thinking".