Having never been to a convention of this type, but having read about some of the wackos that turn up at these things don't you think it's just slightly spooky that people spend a lot of money dressing up as klingons or whatever.
I really go for SF/fantasy fiction but dressing up is taking it too far.
I remember reading about a guy who thought he was Elric reicarnated spent a fortune getting the sword made clothes made,hair bleached and was very miffed when the local police arrested him for wandering down some street waving his sword or "Soul eater" around
Or maybe Ive become a boring old fart who knows!