For instances the place despite a number of believable explanations, they by no means discovered or revealed proof to justify any of them OR there have been no explanations in anyway…
Examples for such being:
Circumstances of disappearance of people or a gaggle as an entire…
Victims who died or who had been discovered useless beneath unnatural circumstances.
Circumstances the place they claimed to be a supernatural factor concerned (ghost/alien/haunted home/reincarnation)
Among the well-known instances of web mysteries.
And the likes….