We know alot about what offends Jesus! Sin, sin of any type offends our LORD, and vulgarity to me would count as sin. And in offending your brother, that is your bretheren in Christ i am referring to.. The word gives us an examply of this, that if your bretheren be offended by meat, to not eat it, although it not be a sin to eat meat, if it offends your brother, it could become a stumbling block unto him. We must be careful about what we do, say and have in our lives that other's are able to see.
Nothing in the Bible suggests that heavy metal music is a sin. Therefore individual people must make up their mind on whether or not music is offensive to them. I personally don't find any music to be sinful. What is vulgar? Isn't that also left up to each individual? What one may consider vulgar someone else may not. I don't find it vulgar for a woman to wear a bikini on the beach. Some people do find that vulgar. So you are saying that if other Christians find something to be sinful then all Christians should. We would be offended at the world if that were the case. We must be careful about what others may see? Is that supposed to mean that as a Christian we must "keep up appearances" to the rest of the world? Do only what the Vatican or whoever may have us do? I'll say again that the Bible doesn't say that heavy metal music is a sin.