The way I see it, anything that makes a sound is playable. Cheap plastic ukes, washing powder boxes, car keys... They all have a unique voice.
Traditional playing might not sound as good as with a proper uke but I'm sure you can pull out some interesting unique sounds out of it if you experiment a little. A friend of mine got a terrible tourist ukulele at a flea market: intonation completely off, fret buzz, even a string missing, you name it. You certainly wouldn't be able to play anything remotely close to a proper chord on it, but it can still make pretty nice music - just not the kind of music you'd expect from a uke
:2cents: