I'm a believer.
We joke about ghost here all the time. I have a grandfather clock that's well over 100 y.o. in the living room that routinely opens it's door even though I've placed pennies under the front corners of it so that it pitches back against the wall.
I saw one up in main in a B&B about 20 years ago - just a little boy standing in a doorway, looked real enough to me.