Wasn't there an experiment where a bunch of people used a Ouija board blindfolded? If the ghost can see, blindfolding the living human being shouldn't matter, as long as their hands could work a planchette.
As I recall, it was a complete and total bust.
That said, I avoid them because a Catholic upbringing instructed me to do so, even though intellectually they're probably harmless. It's hard to break ingrained childhood edicts.
I am curious, though, about this audio Ghost Box thing that Aunt Blabby mentioned. Where did he get such a thing? Did he believe in this stuff prior to using the Ghost Box, or did it make him some kind of believer?