I live and work in Utah, which, for not completely clear to me reasons, is home to a lot of MLMs. Nu Skin, Usana, Xango, doTerra, Young Living, Jamberry (and those are the ones I can just name off the top of my head) are all headquartered here.
For an area that in many ways is punching above its weight class in terms of tech companies, I occasionally have nagging (possibly unfounded?) concerns in the back of my head that one day a lot of these companies will be a hindrance on the continued growth here. I know some people already view Utah mostly as the home of MLMs and I don't know if that does much for attracting forward looking tech investment. That said, these companies have brought a ton of jobs and has certainly helped fund the growth in the area and I have worked with and met a lot of people who seem pretty decent.
While many of these companies aren't "evil", I think the MLM is probably one of the most insidious dark design patterns around. I think the best way of how these companies primarily operate is like the Cassette/CD clubs of a few years past. A small fee gets you a decent amount of "up front value" (Join the club for $30 and get 30% off your first order!) with the expectation that you won't order anything else or forget to cancel the yearly membership fee. This is, of course, all made worse by the fact that is often friends and family who are peddling the high margin health and dietary products with questionable efficacy. Like I said, I don't know if I can call it an outright scam (I know a few people who really like there shakes and supplements and swear by them), but it does drive strange incentives...