Is multi-level marketing ethical, and does a money-back guarantee distinguish it from a pyramid scheme?

"Similarly, Rodan+Fields was established as a cosmetics company by two medical doctors. They began their company by starting out as a multi-level marketing company. The practice of multi-level marketing by companies like Herbalife, Rodan+Fields, Beachbody, and Plexus also is controversial to some. Basically, multi-level marketing enlists a new salesperson by making the individual purchase training and inventory of the company product at a discount and begin selling the product at retail prices, while also recruiting new salespeople as their “downline” salespeople. The idea is that eventually you will make most of your income via the results of your downline salespeople—the people you brought into the business. There are numerous critiques of multi-level marketing, the most notable being investor Bill Ackman’s accusation that weight loss company Herbalife was engaging in a pyramid scheme. A pyramid scheme is an arrangement whose entire whole purpose is the enrichment of the top of the pyramid at the expense of new recruits. Herbalife was able to refute Ackman’s accusations in a lawsuit brought against them by showing that their results were based on product sales rather than recruitment and that they offered money-back guarantees if the recruits were unable to sell the product. Ethical Dilemma : Is the practice of multi-level marketing ethical? Does the money-back guarantee provided by Herbalife provide evidence that they are not engaged in a pyramid scheme? Sources: “Multi-Level Marketing,” Investopedia, http://www.investopedia.com, accessed October 1, 2017; Alissa Fleck, “How Women Making Men Rich Has Been Misbranded as Feminism,” Huffington Post, http://www.huffingtonpost.com, August 28, 2017; Kristen Calderaro, “Why Are Doctors Becoming Rodan+Fields Consultants?” LinkedIn , https://www.linkedin.com, October 29, 2015; Rhonda L. Rundle, “A New Name in Skin Care: Johns Hopkins,” The Wall Street Journal, April 11, 2006, p. B1."