Are they though? Didn't God say that all he created was good? I Timothy 4 says that there would come a day when men would teach that people need to abstain from stuff that God clearly meant to be good.
"Now the Spirit expressly says that in later times some will depart from the faith by devoting themselves to deceitful spirits and teachings of demons, through the insincerity of liars whose consciences are seared, who forbid marriage and require abstinence from foods that God created to be received with thanksgiving by those who believe and know the truth. For everything created by God is good, and nothing is to be rejected if it is received with thanksgiving." 1 Timothy 4:1-4The fact is that nothing God created is sinful. Worshiping the creature more than the creator is. Marijuna isn't sin, loving getting high more than God is. God created everything in this world with a purpose, and everything in this world should be used for God's glory.
Its been claimed by many that certain kinds of music are inherently sinful, that they naturally cause sinful desires. I have even heard that rap music can make one feel a sinful emotion.
All this is claimed without support from the Bible. Nowhere does the Bible say that any kind of music even can be sinful. The Bible is simply silent on that. What the Bible does say is that God created everything for his glory, and that nothing is to be rejected if recieved with thanksgiving.