I think MLM's are comical and hokie, but it's not unethical to provide a product, allow ambitious and consenting people to sell it, and pay them off their production. A lot of real life businesses function the exact same way. Most people in finance, for example, are commission only. It's a risk to only eat what you kill, but it works out for those that make it work.

Nothing I just described is "unethical."

What I do consider seedy is how members of the church in Utah take advantage of church relationships to pedal a product, which I presume happens quite often according to my in laws who live in Utah. My mother in law has a visiting teacher who has some kind of oil she tries to pedal in literally each monthly visit.

Also, as has been mentioned on this thread, if the product being sold is some kind of "snake oil" remedy, that in itself is immoral.

One more thing: in a free market, the buyer also has responsibility when transacting.