Since joining this forum here and learning more about ways to use Social media tools, I have been using FB as a way to get backlinks to my other websites and using them as a source for that type of traffic. I have not placed any adds on FB, but I might give it a try once I master all the uses for this social media aspect.
I have but a couple of links in my posts promoting my own services, and thus it has helped me to bring in some sales. That is what I do with FB for now anyways
Hope my answer helps your question a bit more