Snake oil is an expression that originally referred to fraudulent health products or unproven medicine but has come to refer to any product with questionable or unverifiable quality or benefit. By extension, a snake oil salesman is someone who knowingly sells fraudulent goods or who is himself or herself a fraud, quack, charlatan, and the like.
Two main hypotheses for the origin of the term are as follows: The more common theory is that the name originated in the Western regions of the United States and is derived from a topical preparation made from the Chinese Water Snake (Enhydris chinensis) used by Chinese laborers to treat joint pain. The preparation was promoted in North America by travelling salesmen who often used accomplices in the audience to proclaim the benefits of the preparation.
One source, Dr. William S. Haubrich in his book Medical Meanings (1997, American College of Physicians) claims that the name came from the Eastern United States. The Native Americans of New York and Pennsylvania region would rub cuts and scrapes with the petroleum collected from oil seeps that occurred naturally in the area. European settlers observed this habit, and began bottling and selling the substance as a cure-all. The preparation was sold as "Seneca oil" in mid-nineteenth century, after the local tribes. Haubrich claims through mispronunciation this became "Sen-ake-a oil" and eventually "snake oil". Haubrich's claim, however, appears to be a case of folk etymology, as no further evidence appears to exist for this transformation.
Chinese laborers on railroad gangs involved in building the First Transcontinental Railroad first gave snake oil to Europeans with joint pain. When rubbed on the skin at the painful site, snake oil was claimed to bring relief. This claim was ridiculed by rival medicine salesmen, and in time, snake oil became a generic name for many compounds marketed as panaceas or miraculous remedies whose ingredients were usually secret, unidentified, or mischaracterized and mostly inert or ineffective.
Patent medicines originated in England, where a patent was granted to Richard Stoughton's Elixir in 1712. Since there was no federal regulation in the USA concerning safety and effectiveness of drugs until the 1906 Food and Drugs Act and various medicine salesmen or manufacturers seldom had enough skills in analytical chemistry to analyze the contents of snake oil, it became the archetype of hoax.
The snake oil peddler became a stock character in Western movies: a travelling "doctor" with dubious credentials, selling fake medicines with boisterous marketing hype, often supported by pseudo-scientific evidence. To increase sales, an accomplice in the crowd (a shill) would often attest to the value of the product in an effort to provoke buying enthusiasm. The "doctor" would leave town before his customers realized they had been cheated. This practice is also called grifting and its practitioners are called grifters.
From cure-all to quackery 
The composition of snake oil medicines varies markedly between products.
The government sued the manufacturer for misbranding and misrepresenting its product, winning the judgment of $20 against Clark Stanley. Soon after the decision, "snake oil" became synonymous with false cures and "snake-oil salesmen" became a tag for charlatans.
Popular culture 
- Poppy: W. C. Fields's film about a Western frontier American snake oil salesman complete with a surreptitious crowd accomplice. His demonstration from the back of a buckboard (transparently fraudulent to the movie audience) of a miraculous cure for hoarseness ignited a comic purchasing frenzy.
- Disney's Pete's Dragon : The greedy "Doc" Terminus, played by Jim Dale, gave a testament to the persuasive power of the snake oil salesman.
- The Adventures of Tom Sawyer : Mark Twain presents Aunt Polly as a true believer in various sorts of snake oil, though not always in the form of an alleged medicine.
- The Outlaw Josey Wales: Josey Wales spits tobacco on a snake oil salesman's suit and suggests he use his ointment to clean the stain.
- Flåklypa Grand Prix: In this animated movie, Snake Oil is used as a name for a shady oil company.
- Sweeney Todd: The character Pirelli sells Pirelli's Miracle Elixir to help hair grow and Sweeney Todd and Mrs. Lovett reveal that it is fake.
- Say say say: 1983 music video of the song in which Paul McCartney and Michael Jackson peddle a magic elixir that supposedly increases one's strength instantaneously.
- Steve Earle's "Snake Oil": Singer-songwriter Steve Earle recorded a song critical of the Ronald Reagan administration entitled "Snake Oil" for the album Copperhead Road, released in 1988.
- Red Dead Redemption: A number of missions involves John Marston working with a snake oil salesman, Nigel West Dickens, as a shill, so he can sell his tonics to ignorant farmhands, despite them not doing anything.
- Gypsies, Tramps and Thieves: In the song by Cher, the singer's father sold bottles of "Doctor Good" at a traveling show.
- Emmet Otter's Jug-Band Christmas: A running joke explains the title character's late father had sold snake oil, "but nobody wanted to oil any snakes."
- "Harry Potter and the Half Blood Prince": Arthur Weasley heads up a department restricting the sale of counterfeit magical protection items that wizards claim will protect others from Dark magic.
- Popular internet comedy group Loading Ready Run produced a sketch on The Escapist titled "Snake Oil", satirising the early invention of dishonest marketing, in which a salesman invents and attempts to sell actual Snake Oil.
- The 2013 PC and Console game Bioshock Infinite, set in an alternate reality 1912, has what amounts to a magic powers system that is based on drinking various snake-oil style tonics called "vigors."
See also 
- Rosie Meistel, "Snake Oil Salesmen Weren't Always Considered Slimy", Los Angeles Times, 1 July 2002
- Graber, C (2007-11-01). "Snake Oil Salesmen Were on to Something". Scientific American. Retrieved 2011-12-04.
- Nickell, J (1998-12-01). "Peddling Snake Oil; Investigative Files". Skeptical Inquirer (Committee for Skeptical Inquiry) 8 (4). Retrieved 2011-12-04.
- "The Long Struggle for the Law". Food and Drug Administration. Retrieved 2011-12-04.