Case in point:
A year or so back a "Psychic Medium" and a bunch of people went for a stroll in the old WW2/Siege Tunnels on a "ghost hunt". People paid money for this.
Now this shit is guaranteed creepy, there's no natural light and any electric lights are few and far between assuming they've even got power. The tunnels are cold, damp, and musty. There's also a ton of condensation so there's always something dripping down the walls or the stalactites.
It's also awesome because you run across old AA Guns, Military detritus, and shit like abandoned Generators left over from WW2.
But generally you go in and the chance you'll get carried away and mis-interpret a sound or shadow is going to be through the roof due to the atmosphere.
Everyone swore they saw something, or heard something.
"I saw a shadow move..." "I heard something over there..."
Well I should hope so dumbass there's 30 of you armed with flashlights inside a cave.
Everyone swore blind they'd taken a picture of a ghost.
WW2 tunnels, no natural light, mob of people moving constantly each armed with a flashlight and camera, every surface is at least partially reflective due to condensation, bugs and dust disturbed by the mob, and the guarantee every camera would take a god-awful grain-filled image due to total lack of sufficient light.
You'd think some people may be a bit hesitant right?
I mean what they're seeing on their photo could be dust floating in mid air, dirt on the lens, bugs attracted by light, bad exposure on the image, stray shadow from a flashlight, image artifacting or heavy grain due to insufficient light...
But no. What they had on film was definitely a ghost.
Never have I wanted to collectively punch so many people at once.