Just my thoughts on it as a child. Hallowe'en in general puzzled me; were ghosts, witches and so on real, or not? I remember being really confused about it at the age of five or six: I had very black and white views on what was real, and what was not, with my childish sense of knowing everything. (Santa Claus was most definitely make-believe in my mind!) I loved it when we finished a story, and the teacher asked "could this be a true story?"; usually the answer was no, perhaps because of talking animals.
Then suddenly, Hallowe'en came, and teachers were talking quite seriously about ghosts, witches and the like, as if they were real, but without really saying if they were or not. I remember feeling quite baffled as to why anyone would "celebrate" things which are meant to be scary, and I almost expected to see some ghosts or witches that evening. I was then even more puzzled when I later learned that some people really seriously do believe in ghosts, and claim to have seen them; and these would be the very adults bringing children down to earth with "no, mermaids/unicorns/fairies are pretend".
(My parents were dead against trick or treating, so I never did it.)
Was anyone else confused by it all when they were little?