From Wikipedia:
Snake oil is a traditional Chinese medicine made from the Chinese water snake (Enhydris chinensis), which is used to treat joint pain. However, the most common usage of the phrase is as a derogatory term for compounds offered as medicines that implies that they are fake, fraudulent, quackish, or ineffective. The expression is also applied metaphorically to any product with exaggerated marketing but questionable or unverifiable quality or benefit.
That is all.




says pretty much the same thing.