Multi-level-marketing programs, or MLMs, are as diverse as businesses of any other type. There are scams, there are legitimate businesses and there are both ethical people running those examples, and unethical.
Like picking a martial arts school, you can't clump all "Karate people" into one lump, any more than you can clump all "MLM people" into one clump.
I will say this, I seem to attract MLM peoples like crazy. And, for good reason, as I am highly excitable and future oriented (their ideal)
So, I've tried Quixtar (now re-named back to Amway), Isagenix, and a few others, all with similar, lack-luster results in earnings, but, excellent results in mindset from some of the books they'd had me read (ie Rich Dad, Poor Dad)
I will say this: Everyone should try one MLM, for their excellent training, and ambitious atmosphere. Like going to the MMI, or a great martial arts school - simply being surrounded by positive people, in a positive environment with positive goals WILL affect you... positively.
The reason I suggest everyone should try at least one MLM, is because of two reasons.
1) To experience the thought of true freedom, and develop a passion for it.
Regardless if the MLM is right for you long term, it will still fuel future efforts towards that end. You have the potential for greatness, and an MLM is an excellent segue into said greatness. Understand, it could be the tool that establishes that freedom, or, it could simply be a stepping stone. Regardless, I'd say they're excellent teaching tools of leverage.
2) Their training systems. To experience the training methods of some of the better MLMs (The best I've seen is Market America's) is to experience (again) that taste of true freedom. What they teach is basically time leveraging and practicing what you preach.
Capitalizing off of pre-existing habitual activities, and monetizing what you already do. (this blog, for example, is an example of that - I give this advise for free, but, you reading it here makes me a nickel if you click on some of our lovely sponsors on your right)
What I would suggest, is not to go head-first into the first MLM you stumble across (or more likely, are invited into)
Why? Because they are basically all the same. They have different bells and whistles, and different products, and different people, but they basically start by drawing a circle, then two other circles.
SO: Find an MLM that works for YOU. What is YOUR passion? What do you love? I guarantee you there is an MLM out there waiting for you.
From water to protein powder to gas to pretty much any consumable product you could already know about, there are MLMs about them.
Heck, even Deepak Chopra has one, so why not you?
PS - There are also interesting resources, if you have an MLM that can help acellerate your progress.