I always believed that one should pratice ethics in their lucid dreams just as they would in waking life. That said. I had a diagreement with a freind who believes in the opposite. But before you think he is some evil person question what his reasoning is.
In real life there are actions and feelings that we all supress from time to time. He feels that it's your mind's opprotunity to let go of all those inhibitions. act opon and perform "Bad" things in your dreams to counter effect your feelings while your awake. In return your demons will be satisfied.