I am sure one could fake images, I would have no idea how to, and no reason to do so.
Some would RM - for publicity, attention or just purely because they are bored and see it as some form of entertainment - seeing those who readily believe 'anything' going daft over the images etc.
In this digital world, its easy enough to clone or copy elements into images on a computer these days (we do it when its necessary - in group shots for example). That doesn't mean that an image showing what appears to be a ghost/spirit/fairy is necessarily a fake. Electrical/electronic equipment can be very sensitive to certain 'vibrations' especially in the right conditions..
edit You stated previously that you took some photos of your barn in your field and a really spooky image of a grotesque face appeared on a photograph. You say that if you had seen it in reality, understandably you 'would have been a few miles down the road'.
I have some photographs with what appears to be 'orbs' showing on them (the first manifestation of a spirit or dust specs caught in the light). We have film footage of 'orbs' too - their movement doesn't suggest they are dust specs.