I am having some good results with the scat mat that I have. One of my cats (don't know which one) likes to pee on my washer. Since I put the scat mat on the washer, no more pee. The battery has since died, but it's still working. I'd like to rent some; buying is rather expensive when you need several.

By the way, my scat mat doesn't shock them, just lets out a loud beep.