The word “pseudo” means fake. The surest way to spot a fake is to know as much as possible about the real thing—in this case, about science itself. Knowing science does not mean simply knowing scientific facts (such as the distance from earth to sun, the age of the earth, the distinction between mammal and reptile, etc.) It means understanding the nature of science—the criteria of evidence, the design of meaningful experiments, the weighing of possibilities, the testing of hypotheses, the establishment of theories, the many aspects of scientific methods that make it possible to draw reliable conclusions about the physical universe.
Because the media bombard us with nonsense, it is useful to consider the earmarks of pseudoscience. The presence of even one of these should arouse great suspicion. On the other hand, material displaying none of these flaws might still be pseudoscience, because its adherents invent new ways to fool themselves every day.