I feel it depends on where they're from. Ones I shoot on farms that are well away from towns are clean enough and the only food in their crops is grain, chicken feed etc. These ones I feed to the ferrets whole, generally freeze them whole and defrost one at a time as needed. I have often thought they'd be ok to eat but always have enough bunny and venison so haven't tried.
Ferals that are feeding in towns, even if they roost away from them, are a different story and are pretty manky, eating all sorts of crap and often scabby with missing toes etc. I wouldn't feed these and if the hawk catches