"The Charlatan", by Pietro Longhi. Credit: Wikipedia.
MLM watch is an excellent web site with many, many links showing the fraud inherent in MLMs. MLM watch is a sister site of Quackwatch.
But aren't these two different things? MLMs are an economic scam, Quackery is a medical scam.
Not at all! MLMs, as the pathetic earning of 99%+ of MLMers shows, are de facto pyramid schemes: only a few at the very top make money, by getting it from the "downline" -- those at the bottom of the pyramid. But how can the upline get the suckers in the downline to give the upline money for nothing, without running afoul of anti-pyramid-scheme laws?
Well, one must have a product -- officially -- and one of the most common products in MLMs are all kinds of quack-based lotions and potions, which cost almost nothing to produce and can be sold for a huge markup to the suckers, as long as one claims all sorts of non-specific "health benefits".
Conversely, many quacks who want to sell worthless nostrums try selling it through the MLM route -- this allows them both to dump the stock on the suckers by telling them that it is a product "everybody wants", as well as avoid the publicity or scrutiny that would occur if they sold the product in regular retail stores.
Among others, quack medicines sold the MLM way include Herbalife, Privatest, Seasilver, and numerous others. When not actually worthless, the product sold -- such as Quixtar's Nutrilite's vitamins and minerals -- are almost invariably (as always with MLMs) far, far more expensive than the generic brand would be -- often ten times as much.
MLMers like to claim that, sure, their products are ten times more expensive -- but that's because it's "natural" and "special" and "unique". Nonsense. It's ten times more expensive because it's an MLM scam. Gotta pay that upline!
If someone offers you any sort of vitamin / medicine / food supplement / treatment through MLM, run. If the product isn't actually quack medicine, it's the same vitamins or supplements you can get elsewhere -- at ten times the price.