Warning: this is going out of topic of Supernatural.
I agree with you, what we see in the media also concerns me. If I had a child, I can imagine being scared of what they will become, seeing that music nowadays are all about sex, partying, glamour, money, and so on. and that is what is considered in style. But I have a friend with 15 and 13-year-old daughters. I'm pretty close to them, they sometimes spend the night at my place. I was pretty concerned about the 15-year-old, despite being raised according to Christian values, teenagers are still very easily influenced by their friends, so I was kinda scared of how she would turn up. But I was happy when she invited me to her baptism a couple of weeks ago. She has made the commitment to follow Jesus. Although I didn't raise her, I was happy for her. So I guess while it may be hard for the young people not to be influenced by what the media offers today, it is not impossible. it depends on how they are raised, and pretty much on who they spend their time with. The person's character also plays a role, of course.
However, if it bothers you, maybe steering clear from movies/shows with obvious against-Christianity values would be better. I mean, Supernatural is clear that it's about supernatural beings, or true blood, for example, I'd also steer clear of that.