Yes, marketing works. The Saturday Journal writes about Michelle Nimmons, who runs the Denmark-Olar Teen Life Center in Denmark, SC. She and her staff (using nothing but marketing techniques like billboards, classroom sessions, free dinners and condom distribution) have cut the teen pregnancy rate by more than 60%. It's now, by far, the lowest in the state, a fraction of the rate in the next county.
Most marketing problems aren't intractable. They are solved with persistence, consistency and attention to detail. When marketing doesn't work, it's usually because the product is lousy. But the second reason is that the organization picks too big a marketplace in comparison to the resources they have available. I have no doubt that if Michelle tried to do her work in the entire state (with the same staff), she'd fail.
By overwhelming the market with her message, and by creating a platform for it to spread, she's proven it can work.