Snake oil was a real product. It was a traditional Chinese medicine that was brought to the United States in the 1800s by thousands of Chinese migrants who came to the country in order to find work building the Transcontinental Railroad. They brought with them their families, their culture, and their medicines. One of these was snake oil, extracted from Chinese water snakes, and used to treat arthritis and joint pain.

As word of the healing powers of Chinese snake oil grew, many Americans wondered how they could make their own snake oil here in the United States. Because there were no Chinese water snakes in the American West, many healers began using rattlesnakes to make their own versions of snake oil.

It was Clark Stanley, the self-styled “Rattlesnake King,” who successfully capitalized upon this. Stanley traveled across the United States, dressed as a cowboy, and put on shows. In front of a crowd, he would slice open a live rattlesnake and throw it into boiling water, and when the fats of the reptile rose to the surface, he would skim the top and bottle up the oil. Throngs of people lined up at his shows to buy the stuff.

Stanley claimed that he learned about the healing power of rattlesnake oil from Hopi medicine men. In 1893 he and his rattlesnakes gained attention at the World's Columbian Exposition in Chicago. Later he went on to establish production facilities in Beverly, Massachusetts and Providence, Rhode Island.

However, there was a problem with Stanley’s product: Stanley's Snake Oil didn't contain any snake oil at all. In 1917, federal investigators seized a shipment of Stanley's Snake Oil and found that it contained primarily mineral oil, fatty oil believed to be from beef, chili peppers, turpentine, and camphor. Stanley was charged for fraudulent marketing and fined $20.

Ever since then, the term “snake oil” has been established in popular culture as a reference to any worthless concoction sold as medicine, and has been extended to describe a wide-ranging degree of fraudulent goods, services, ideas, and activities such as worthless rhetoric in politics.