You can still get addicted to herbal cigarettes. It doesn't harm their voices because the ones that are really conscous about it don't inhale, they just take it in their mouth and blow it out.
Whenever you watch someone smoke on stage or in a movie, you can always tell which people actually smoke in real life, and which ones look intolerably ackward doing it.
"If you are going to do something, do it well. And leave something witchy."
-Charlie Manson