HAHahahaha. We hear that sometimes! It's a bowling ball, how dirty can it get?
For fun (or to gross yourself out!) read this:
http://theneffgang.blogspot.com/2008/04/never-lick-your-fingers-at-bowli... (I especially got a kick out of the comments!)
The bowling ball I've added to this post is a Quantum Bias, sort of an off-white ball. This ball was thrown for 2 1/2 games at Alan's Crosley lanes. Yuck. I know from from personal experience that the last lane of the house has a really bad belt that leaves all sorts of debris on your ball!
So how can you clean it? Well. 409. Windex. or drop it in our the Ultrasonic Bowling Products Sonic Revivify at your local pro shop! You'll get the hook back while you're at it.