I am a huge Harry Crews fan. No one writes quite like this hyperrealistic gothic southern writer, and no one can create such bizarre characters in so few pages. Indeed, I have read "The Knockout Artist" several times, and always get something different out of it. As always, Crews concerns himself with the larger questions in life, especially how to maintain one's moral compass in a surreal amoral world (here its New Orleans), but he also creates characters as compelling as one can find in late 20th century fiction. You will root for the main character and never forget those that he meets along the way.
To address one of the other reviews, in Crews' world, it is hardly surprising that there are people who would pay handsomely to see someone knock himself unconscious. I am sure that in the underbelly of any major city, (which certainly would include New Orleans!) there are those who have desires far stranger than this.
I urge you to read this book. If you like it, run out and buy "A Feast of Snakes," which is just as good.