There is one important criteria for including a haunting in the map, and it relates to localisation.
It's arbitrary but I'll only be happy putting something on a map if I can pin it down to within a few hundred feet. This is because I want users to have a chance of seeing something when they explore. So, small parks or short roads are OK but I've had to veto some promising cases. Eg there's a case of a Viking girl who used to terrorise truckers as they drove along a road in the north of England. Great! I thought.
But then I checked and the road stretches a fair width of the north of England and there was nothing to say exactly where it took place.
Typing that, I remembered another criteria: I'm not really interested in one-offs as they could be anything. But if a location has more than one sighting, even if they are all one-offs, then I'd probably put it on. That could mean that the location has some affliction with ghosts even if they're all different. With a one-off sceptics could say that it was a passing mental aberration.
And BTW, I've come across a few hoaxes in my research too. Usually previous pub landlords who have concocted a story to enhance trade.