I don't believe in haunted houses.

I do believe in haunted people. In fact, they're exceedingly common. People can be haunted by memories, particularly the memories of people they've lost. Or, they can be haunted by their own mortality, the knowledge that some day they won't be around anymore. There's nothing supernatural in either of those, though.

I wouldn't go so far as to say that ghosts (in the supernatural sense) 100% don't exist, but I'm pretty sure. 90%.