Glad to know that Litje is not the only woozle with this hobby....
None of my others dig in the pans, whether just cleaned or dirty, but Litje
will dig in and empty even a dirty litterpan if he's upset with me for
anything (Revenge, thy name is woozle.) He used to delight in digging in the
clean pans, too, just for something to do, until I learned this little trick
- Lightly mist the fresh litter with water.  When I did this, he would still
use the pan for its intended purpose, but suddenly lost interest in it for
recreation.
 
BTW, I use alfalfa rabbit chow for litter.  I've had fewer problems with
smell and dust than with clay litters.  The ferrets sneeze less, too.
 
Blessings,
Carla & the Woozlemaniacs
Litje, Turlough, Gaoth, Quidni
[Posted in FML issue 1460]