William Goldman, in his book Adventures in the Screen Trade wrote when it comes to deciding which movies will appeal to the public “Nobody knows anything. Not one person in the entire motion picture field knows for a certainty what’s going to work,” he said. “Every time out it’s a guess - and, if you’re lucky, an educated one.”

So there it is: Nobody knows anything. It doesn’t matter who said it (was it Sam Goldwyn?) it is a truth which ought to be universally acknowledged.