From my experience, most J-dubs seem to have the same mix as lazy/hardworking/deceptive/honest employees as the general population. The trouble seems to start when J-dubs hire other J-dubs, either as employees or as contractors. Suddenly they're looking for favors, expecting special treatment, or ignore your project in favor of non-JW clients since "you'll understand".
I hired a JW for a construction project once, but never will again. Even my uber-JW parents decided long ago to stop hiring JWs as employees or contractors.
General rule of thumb:
JW+"Worldly person"+$$$= Normal result
JW+JW+$$$= PROBLEMS!