As someone who works in advertising I try to do my part by only taking clients that I trust sell something quality and do business with integrity. I could make a lot more money if I just sold anything and everything. I know people that market tobacco products on Facebook, for example. Those contracts are extremely lucrative, but I simply could not feel good about promoting those products.
I would not be able to do what I do (from a moral standpoint) if I just advertised for everyone. I enjoy what I do because I am able to promote people and companies that do something positive. There are a lot of scammers in my business, and I was tired of watching the least honest people get the best results (because they can afford top agencies) and the smaller clients actually doing something positive get screwed by dishonest marketing people.