There's no final decision, but the U.S. Federal Trade Commission has taken a step toward possibly classifying many multi-level marketing firms as pyramid schemes. As it stands now, three MLS teams have multi-level marketers as shirt sponsors and this could be bad news for them.
One of the biggest MLMs in the country is Herbalife, the LA Galaxy's primary sponsor, and they are one of the main companies being targeted in this court filing. The other two MLS shirt sponsors that are potentially affected in this case are Real Salt Lake's LifeVantage and FC Dallas' Advocare. Amway, probably the best known MLM, was the San Jose Earthquakes' shirt sponsor from 2009-2011.
I can't pretend to be an expert on any part of this story (and I'll highly recommend reading The Verge's article that has more of the big-picture details), but this can't possibly be the kind of the thing that is a positive.
Then again, money is money and as long as these companies aren't declared illegal, I suspect MLS will gladly keep cashing their checks.