Interesting, useless info, that is unless you don't like spiders.
Another reason to roll off the top here in Florida is as a 1st responder I have been to several calls where people have been bit by a spider who had hidden up under the fold. Every time I have noted the the paper was rolled under.
When the paper is rolled over the top, the spider drops down to the floor but when it is rolled under, the spider is on the top of the paper and he drops on your wrist. Ouch, a bite.