When JOHN VALBY sits down at the piano, it is hard to decide whether to laugh or listen first. Because what the 67 year-old musician does is mix his musical talent with a mad-cap variety of dirty songs that no one can resist laughing at. It is an interesting blend that has audiences everywhere coming back for more. They want it all ... the dirty and the clean. Much of the Dirt comes from the Ya-Ya-Ya-Ya-School of Dirty Songs, but a lot of it comes in the form of Valby compositions and made-up on-the-spot limericks. The Clean stuff is comprised of rousing classical arrangements, ragtime tunes, popular songs and Valby originals.