He discovered that audiences laughed whether the tricks worked or not.
Tommy Cooper was a British comedian / magician who used magic props not to deceive an audience, but to make them laugh. His jokes were old, his props were standards from the magic store, and most of the time his tricks didn’t work or he inadvertently exposed them. But his character and delivery were priceless.
The vase trick
The spotted handkerchief trick
The magic cloak
The glass and bottle(s) trick