do sleeping people eat spiders?

I was told that spiders like to crawl into people’s open mouths when they sleep. Presumably because mouths look like a nice place to set up a web.The unconscious person then swallows them without knowing.
I’ve heard this theory several times in the past year.Each time the theory comes with an estimate of the number of spiders people consume in a lifetime.This number ranges from 1 to hundreds.
Is there any reason a spider might want to crawl into someone’s mouth? And if so, how could the number of spiders in a lifetime be estimated?

I know I do. Five, six a night. That’s why I keep a nice cup of melted butter by my bed.

This has been asked many times before:
http://boards.straightdope.com/ubb/Forum3/HTML/000061.html
http://boards.straightdope.com/ubb/Forum3/HTML/002445.html
http://boards.straightdope.com/ubb/Forum3/HTML/004905.html

and now,
http://boards.straightdope.com/ubb/Forum3/HTML/007007.html