NOTE: THIS IS ANOTHER DUMB DEBATE.
Music has undeniable psychological effects. As you mentioned, if you are insane, then music can definatley affect you. Depending on your intelligence and integrity, music will, undeniably, in some way or form alter the way that you think. While any retard can tell you that music is not directly responsible for anyone's actions: "I don't think the music literally makes people do it.", it will certainly influence, to some degree, your beliefs and perspective of life, since people are a direct result of their environment. "Bad" is also a relative term, which makes the question of this debate incredibly stupid and difficult to debate since 'bad' can mean different things to different people. What should really be asked is if music can influence people to commit certain behaviors that they would not have committed had they not listened to that music.
An example of how music can influence people heavily is religion. When missionaries try to convert people from third world nations, who are often uneducated, they will use music as a means to draw the third-world inhabitants closer to their beliefs, and history has proven that this approach influences people. If music can influence the way you think, then it also influences the way you act. This applies to all genres of music, including rock.