I think for the average person, that's probably not the case. If you don’t ever go beyond your everyday “beta consciousness,” you're somewhat protected. It’s the one incident where ignorance is truly bliss.
However, if you’re naturally more receptive to the supernatural (i.e., if you’re naturally psychic) or if you’re actively dabbling in the occult or performing any kind of spiritual practice—or all of it—then yes, it could be dangerous to dwell on such negative things.
Back in the 1980s and ‘90s, I had some really horrible experiences because of this. I was fascinated with the supernatural and the occult and read a lot about it. And then I listened to a radio show and decided to “communicate with the dead” to entertain myself… a very bad mistake. The whole story is described here.
After I got rid of the evil spirit, I tossed all my paranormal and occult books and movies and focused on “lightworker” type stuff. For a while. But it was too tempting.
The thing lay dormant for seven years and then came back (IF it was actually the same spirit, I’m not sure). This time, the experience was more poltergeist-like but equally scary. Thankfully, my friend D. knew a very powerful Reiki master who had helped her out of a similar situation and who helped me, too, get rid of the spirit.
When I first met D., she was sweet but very dark. She drank a lot, took a lot of drugs, and was a true wild child. And like me, she was a natural “sensitive” or whatever you want to call it.
I once visited her apartment and was shocked: all the walls in her bedroom were painted black, there were skulls of small animals on shelves and posters of Baphomet on the wall, and her favorite music was the equivalent of death metal.
She was plagued with nocturnal astral attacks where dark hands would come out of the walls trying to grab her, she said.
She was so terrified that when she met W., our later Reiki master, she did everything he told her to do: she repainted her walls, replaced her black leather outfits with white and bright rainbow colors, replaced the death metal with classical music, threw all the skulls and devil posters in the trash, and stopped reading and watching any kind of sinister, dark stuff.
It did work—the next time I saw her, not just her appearance but her entire aura had changed. And it kept the bad things at bay, she said.
Bottom line is this: If you’re just an ordinary person who lives on the level of highest density, dark movies and books, etc. can probably muddy your aura over time, but do little else.
But if you’re someone with certain (extrasensory) abilities, or if you are engaged in things like magic, certain types of meditation, psychic training, spirit communication, Reiki, channeling, Ouija sessions, automatic writing, OBEs, divination, etc., then you need to be much more careful.
Once you know things that others don’t and have seen things that others can’t—i.e., once you’ve taken a peek through the veil—you will be held to higher standards than the “herd.”
But even if you don't do anything dark and questionable, as soon as you engage in spiritual practices to "raise your vibration," you become something like a beacon in the night to both the Light and the Dark Side.
So you'll need to learn how to protect yourself... and you'll continuously have to watch and examine your personal ethics and make sure your intentions and motivations are pure. (Read my blog post, "How to Avoid Getting Sucked in by the Dark Side.")
As Spiderman’s uncle said, “With great power comes great responsibility.” That’s a true statement, so you need to decide how much risk you want to take.