I got something called a Bike Jacket, I think that's what it's called, so I can hopefully take my bike in hotel rooms. It's a cover that your bike is completely zipped up in. It zips at the top, so no matter how dirty the bike, the mess will stay inside the "jacket". It looks like it's made of vinal. Haven't had a chance to use it for taking my bike in a hotel yet, but I don't see how they can say no. They might not even notice it is a bike in there, with it completely zipped up.

EDIT: I found it, here it is...

http://bikejacket.com/features.htm