Shaming does help change teenagers' behaviors, but it does so in the worst way possible. It makes them feel scared and miserable and unable to express themselves properly in fear that they will be shamed again. Fear does work, though, and that's why shaming seems to work so well usually.
I definitely think that shaming does help changed the behaviors of some teenagers. I think that when some of them are made aware of their issues, it proves to be a catalyst to them changing their ways. But I also think that it negatively affects a lot of them as well.
Teenagers are very concerned about their image. They are concerned about how they present themselves to others and of course, how others perceive them. So to that end, yes, shaming is a powerful force to get teenagers to change. Obviously they don't like it, but I think that's because they know it works.
It's certainly better than beating someone. If you feel shame because of your actions, you are less likely to repeat them. Teenagers are especially conscious of appearance and perceived status. To be forced to engage in some publicly demeaning or embarrassing activity seems like a much better solution than beating them, or arresting them and tossing them into our travesty of a justice system.
Shaming only serves to ruin a teenagers' mental state. It hurts their self-esteem and can cause many different things such as suicide or even attacking other people. It is never good to make someone feel down such as shaming a person for something they did. Shaming should not be used but rather we should employ a method of just punishing them for what they do.