White Sheets=Ghosts?

How about a Halloween-related question: for many years (generations, perhaps?) a white sheet with black holes for eyes is the standard “ghost” costume. Why is this so? Generally, when people report seeing a ghost, they claim to have seen something that looks like a human, albeit perhaps translucent or transparent. (Actually, I think there are quite a few sightings where the “ghosts” seem entirely solid and only become identified as such when they abruptly vanish!) So — have some people reported seeing apparitions which appear to be human figures covered by white sheets? Any information would be appreciated!

So how would you dress up as an amorphous blob, given ordinary household objects? Stapling marshmallows to your jumpsuit?

Back in the day before really good ways of telling whether or not a person is dead people weren’t put in the ground right away. Rich folks would stick their dearly departed in a mausoleum for a while until the body started decaying and everyone could tell they were good and dead. The last scene of Romeo and Juliet took place in just such a mausoleum. Generally, having a body just sitting there was creepy and icky, so they were draped with a big piece of cloth to make things less creepy and icky. If that person were to “raise from the dead” more than likely the cloth would come with them. Hence, the “ghosts wear sheets” phenomenon.

An earlier thread on this subject:

http://boards.straightdope.com/sdmb/showthread.php?threadid=7291