I've only had one legitimate interaction with a MLM person, one of my friends got hooked into one in college so I agreed to go to lunch with him and someone at a higher level. Because I didn't mind getting a free lunch and so after the meeting I could tell my buddy the problems with it.
So for some reason during lunch the higher up guy asked me who my favorite economist was so I listed off a half dozen (I was an Econ major), he kind of looks at me with a blank expression then tells me about some guy who nobody has ever heard of who wrote a 'book' in support of the company. I almost felt bad letting him buy lunch.