Just like any other thing in our world, Art can be good or bad.
The problem is we can't easily distinguish them. There are many people that believe any kind of art is good and respected. And you can't convince them that it's not true.
Imagine, your child has a couple of friends. If you know that one of their friends is not really a good friend and they may lead your child to illegal activities, you try to keep your child away from those people. This is because they affect the behaviour of your child. It's not only about children, even an adult person is affected by people around.
Now imagine there are people with the same mind as those bad guys, they may not speak to you or your children directly but they create so-called Art and spread it across the world. You and hundreds of other people watch it and appreciate it. Obviously Art is a reflection of a mind and that reflection has a reflection on the viewer's/listener's mind.
As soon as you appreciate that kind of Art, your mind accepts it and you are affected or rather infected with the produced waves from that Art.
This is even more dangerous with music. Because its frequencies directly go to your mind and you never notice. These so-called Arts affect the society and spread quickly.
Be careful and don't allow Trojan horses enter your boundary to destroy it.