That looks like classic double exposure.
As for evidence we can't collect yet, it doesn't matter. All claims are open to revaluation.
A lot of those photo seem to be camera artifacts.
This one, with my amateur knowledge is most likely from the flash. The over reflection from the rail roads points to a bright flash. The human visage and body, which is probably dust reflection/refraction is recognized as such, as the human mind works tireless to find those shapes. Its a form of paradolia (sp).
The stair case ghost, is only picture my thinks is of a real ghost. Myself I find it lacking.
Photo could be be used to collect items of ghost, but their would need to be an explanation on a ghost appears on film but not the eyes, since the camera is capturing the same photons as our eyes are.
There also the fact that ghost photo only started appearing when camera became available to the general public, then increase when photo trickery became possible, such the double exposure.
The classic Orb photo only start showing up when flash photography was in common place. There has never been a photo of an orb taken without a flash.
I don't think I could ever declare an experience was a ghost. With knowing how easily the mind tricks itself it would be hard for me to eliminate all those possibilities. And even if I could, I would be contradicting myself by saying it was ghost.
It would. 'I cannot explain it. Therefore I am explaining it.', which goes against my attempts at intellectual honesty. The most I could say is an experience that lacks explanation.