A few months ago we had a thread about ghosts. I just thought I'd post a link here that has some explanations about ghost sightings. From some of the links, it shows that people have found that low frequency sounds can cause people to think they are witnessing ghosts:
http://skepdic.com/ghosts.html
http://skepdic.com/ghosts.html
It's not the side effects of cocaine, so then I'm thinking that it must be love