There's something else going on here - reversion to the mean. Think of your health as a curve that goes up and down. On average, you're probably pretty healthy. Sometimes less and sometimes more. When you're sick, no matter what you do, you'll probably get better. So as long as whatever treatment you do or don't do doesn't make you a lot worse, you will probably get better. Drilling a hole in your skull might seem to cure depression, the common cold, or hemorrhoids, as long as you don't drill too deep or get a bad infection that kills you. Rubbing your ear, walking in a circle, drinking infused water -- almost anything, including eating sugar pills, or just waiting, will seem to cure you most of the time.