That problem is easily solved. http://en.wikipedia.org/wiki/Anal_bleaching
EWWWWWWWWWWWWWWWWW!!!!!!!!
Otherwise, I don't want to know how you know about this practice.
Or desire to want this done. Or to do it.
I'm sure people that go to med school to train to look at "holes" all day long don't care.
Besides, early attempts at bleaching the other end led to some pretty bad dental problems.
Will history repeat?