There are a lot of variables to MLM and for one as you mentioned if they don't have a product that has value it's not worth looking at, if the MLM structure doesn't require the first in line and on down to still produce sales on a monthly basis then it is a pyramid scheme and third it's only a good fit for a certain type of person that is disciplined, consistent, and a people person.
RE: Multi-Level Marketing (MLM) and Network Marketing, is it Worth it?