In college, a group of friends and I would research haunted/creepy/abandoned places and drive out to explore them. We'd often get places from websites, books, hearsay--basically any way we could back then, so it's safe to say a decent portion of our leads were probably bullshit or made-up. Regardless of that, we explored our fair share of abandoned houses, mental facilities and haunted areas. Realistically, the biggest danger we ever encountered would have been angry squatters, but you never know (we did hear a woman screaming for help and what sounded like a gunshot at an abandoned mental facility, but after exploring extensively and finding nothing, someone was probably just fucking with us).
One time was different, though. We'd gotten a lead about a small lake in the middle of some woods where a large stone was used for rituals. We figured it was probably all bullshit, but it was close to a good diner and we figured, at worst, we'd get a good omelette out of the trip. We got to the forest about dusk and parked the car and headed into the woods. There was a faint footpath that you could tell was used with irregularity. We pressed onward and knew we were strapped for time, as we didn't bring any flashlights with us (we planned to get there much earlier in the day than we did) and the forest canopy was making it much darker than it actually was. We ran into the small lake which we'd read about, but didn't see any large stone or something that might be a centerpiece for the rituals we'd read about. The footpath went deeper in to the forest, so we decided to follow it for 5 more minutes and then turn back.
The path slowly began to ascend a small hill and in the distance we could make out some dark blobs that appeared to hovering in a slight haze. Again, it was pretty dark by this point, so it was hard to make out exactly what we were seeing. We approached slower and realized the "haze" was actually a tall chain-link fence. That's not the creepy part, though. The part that unnerved us was what the dark blobs were: every ~10 feet on the fence, there was a dead and decaying dog strung up to the fence, attached by a dead snake wrapped around the dog's neck and through the chain links.
The fence was padlocked with a chain but not very tall--we could have jumped it, but it was dark and we had no flashlights. It was on the top of a hill and we weren't able to make out what was inside the fenced off area, as it turned into a fairly steep decline. We let fear get the better of us and ran all the way back to the car, sitting in silence the entire drive home.
I've always meant to go back to that place, even years later now, but I had such a feeling of sickness and dread that I can't bring myself to. It's almost an unspoken rule that none of us even bring up that place with one another.