Church of Awesome #24 - Are Self Help Gurus Con Artists?

Are self help gurus con artists? I have been thinking about this for a while as I listen to Behind The Bastards podcast. 

I know a lot of good people who just want to make people's lives better. However, I also see a lot of grifts and snake oil being sold as self-help tools. 

What is the difference between a positive influencer and a con artist?