Why????
It has soap and bubble bath and human skin cell debris in it. It can't taste good!!!!
But every cat I've had does this.
Or they get in the shower once I'm out and lap water from the shower floor. My creamsicle tabby can't wait for me to get out so he can do this.
BUT - if the water in his dish has been standing for longer than half a day he sits in front of it and won't drink, with the [impatiently tapping his fingers emoticon} over his head!!