[It should really be "only ghosts invited" if it's a Ghost Conference.

http://www.oregonghostconference.com/

"The 11th Annual Oregon Ghost Conference is the Northwest’s largest paranormal convention and attracts visitors from all across the west coast and beyond. Come enjoy a weekend of ghosts at the coast. Attendees
will connect with and learn from some of the top paranormal experts in our area."

[there aren't any honest ghost hunters that I know of. The Ghost Hunters are such bullshit artists.]