When you ask somebody to try their own hand at something before criticizing your efforts, you have violated Ebert's Law and lost the argument. Roger Ebert is not a filmmaker, but he knows what he likes and doesn't, and has every right to say so. Similarly, people don't need to be chefs to recognize a good restaurant, or musicians to appreciate a symphony.
Person 1: Your story is rubbish!
Person 2: I bet you couldn't do better!
Person 2 has violated Ebert's Law