Brysling has a point, for some spirits/ghosts are an act of fiction, others, they're real. it comes down to belief, since there's very little evidence on them that hasn't been fabricated.
personally, spirits are real, i've had to deal with them my whole life. know how many don't believe in spirits, and i'm a fairly logical person, you need to rule out all possible answers before going to the conclusion that it's a spirit. feel a random chill, look for cracks or open windows where a draft could get in, random noises, commonly thats just the normal creaks of a building. orbs in photographs are the easiest to disprove, 99% of the time, it's light reflecting off dust in the air.
you're not being fluffy, don't worry, like i said, many don't believe in spirits and there is almost no evidence of them being actually real things, it's a leap of faith really until you experience it for yourself. research it, and draw your own conclusion.