This is not a behavioral issue--I don't know which of my cats did it, but I suspect Spike, who likes to mark things from time to time (and no, he doesn't have a urinary infection). I was stupid enough to put off buying a rubber sheet when I bought a new bed a few months ago. Now it has a nice, stinky, yellow stain. I don't know why someone decided to leave their mark--no one ever peed on my previous bed. Does anyone have any idea about how I can get the stain and odor out so that it won't bother me? (Yes, I know that the cats will still be able to smell it, but if I buy a new bed, chances are that somebody will then mark it, too.) Oh, and the mattress can't be turned upside down to hide the scene of the accident.