My neighbor sells Mary Kay. From what I can tell, she's not really making any "real money" doing so because she is still working full time (making great money). It's probably OK for "spending money", but she had to buy a TON of stuff to get started... plus she has to keep an "inventory"... plus there's a lot of pressure for her to go to the conventions and workshops, all of which cost $$.
In the last three weeks, she has tried to schedule several "events" at her home an has had to cancel. People either love the stuff or they don't. Most people DO NOT like retail parties, so you won't get many repeat customers, just lots of "one time buyers".
I would not rely on this as your sole income source. It's kind of a pyramid thing too... there are people above you and I think you earn a higher percentage per sale if there are representatives "below you".
The pink Cadillacs are few-and-far-between. We have 4 women in a 6 block radius who are representatives... none of them drive the shiny wheels.