This is just my two cents on the matter.  I think ferrets have evolved to
be immune to the taste of bitter apple.  My first few ferrets hated it but
my newer ones actually like it.  But now my older ones have realized that
digging on feet is just as annoying as biting!
 
Joy Smith &
Lucy, Theo, Tabitha, Zorro,
Scrawny, Psycho, Pebbles, & Fat Albert
[Posted in FML issue 2687]