Do ghosts exist?

Yes, lenlenlen1 , "logic" explains a lot but not everything.
Just as "humor" is often appropriate but not always.

There are some occurrences that are just not explainable by any means, be it logic or scientific testing, but they do happen and they happen to people who would really rather they not experience them whatever the explanation is.

Often they can be looked back on as "well, that was odd. That was cool. That is totally without explanation " and they would be interesting, and perhaps informative, to tell others about BUT in the telling the response is all too often along the lines of "you are crazy", "you were drunk", "you are an idiot for even thinking this thing happened" and so the stories are not shared.

It is very likely that there are a heck of a lot of stories that are not being told (except perhaps in a more private setting) because of the backlash that all too often follows the telling.

As far as debunking anyone's inexplicable experience … it's so much easier to make a blanket statement of "you are mistaken!" and considering the case closed.