I had a dream once, which made an impression on me.
I was part of an elite team of FBI agents or something similar (think the Behavioral Analysis Unit, if you watch Criminal Minds). We spent most of the first part of the dream chasing a particularly vicious child rapist/murderer. It was very exciting and featured a lot of running around, driving in cars, and dodging traps set by our suspect. Some of these last were quite cruel, designed to capture and kill slowly, inescapable doors covered in spikes that closed on one, etc.
We finally tracked the perp down to his home, a single-wide trailer in a rural trailer park. It looked run-down, but fairly normal: a broken-down truck parked outside, flower pots with straggling plants in them hanging from the makeshift roof over the driveway, dried grass growing through cracks in the cement.
But we got there too late. He was still alive, but only barely--one of our agents found him sitting in a lawn chair next to the truck. He had used a piece of broken glass to castrate himself. The dream did not stint on the imagery; it was bloody and horrible.
Our entire team wandered around, supposedly looking for evidence, but really quite distracted by the scene we'd discovered. We talked about why on earth he might have done it, what could have been going through his head, and how gross the whole thing was.
But oddly enough, none of us were particularly disturbed. Yes, it was disgusting and bizarre and horrible, more so than even what we usually saw, but... it wasn't going to </i>stick</i>. It was more a curiosity, a one-up story to tell in the locker room, than anything that shook our basically good view of life and humanity.
I want that kind of groundedness in my real life. To be able to dwell next to the nastiest bits of human evil and yet find it curious or odd rather than terrifying.