Mine hate the bathroom period!
It's my fault though, that's my "carrier room". It's the room I put them in when I need to get them into carriers. Its the only room with no where for them to hide that I can't get to.
I had a cat growing up though that loved to play in the sink when the faucet was running a slow drizzle, he liked to splash the water all over-mainly onto the mirror. He got so spoiled that he'd actually pull the drainplug out of the sink if we didn't leave it running for him when we left for the day!