In my opinion, torture is never justifiable, and both mental and physical methods fall into that broad category. I don't like to see other people in pain, especially when it can be avoided. There's got to be a better way to get the information.
Besides, it frequently produces false information or nonsense from the person being tortured, who just wants the paint to stop. Or at least that's what I've read in many studies (please correct me if I'm wrong- I'd like to know).