IMO

MLM/direct marketing is a means of getting a product rapidly to the consumer (end user).

In this case, there are 3 things,
Product -> Should be wanted, useful, and generally consumable/short useful life so that ithere's repeat business

Consumer -> the product should hit as wide a consumer base as possible, for instance, shoes, makeup, dietary produts, health supplements.

Distributor -> incentives for the distributors to go out and sell the products. (and not just do 'recruitment'), by giving discounts (usually scaled to volume).

When an MLM focuses TOO MUCH on the 'distributor' element, and ignoring the consumer base and also the product, u should be very suspicious. After all, volume, products and consumers are what drives any kind of business. The distributorship is just an added advantage, but not the 'fundamentals' of the business.