I am no ferret expert as I have only one at this point but I did happen to
start out with a pretty difficult, defiant baby.  I noticed very quickly
that scruffing only made my Rocky come back and bite twice as hard.  That
might be what's happening with Lizzy.  Other than saying "NO!" I don't
think reprimanding is such a good idea.  I used Bitter Apple for a while
then switched to Ferretone.  Rocky learned very quickly to not bite
everywhere except the foot, which he only does now if he is under the
covers on the bed with me.  Also, sometimes he does it when I'm on the
computer to get my attention.
 
It doesn't really bother me, but does bother other people who visit and
with whom Rocky is more tempted to taste their toes.
 
I found the most success with Ferretone--if he comes over and licks my
feet instead of biting, I put Ferretone on and he licks some more and
forgets about biting.  Sometimes when I don't have the patience to deal
with it, I put him in his cage for a short time.  But this never really
works; he either takes the opportunity to eat or goes into his hammock.
 
In general, I don't think punishment, especially physical, is a good way
to train any living creature.  Maybe you could put Ferretone on your
hands before picking up Lizzy, but my main advice to you is to stop the
scruffing, as I think it makes a defiant ferret even more defiant.
 
Rocky says, "I'll show you.  You think you can scruf me?  Just because
you're bigger than me?  Nobody scruffs me!  I don't have these sharp
teeth for nothin!  Nobody's gonna push me around, not even my mother; not
even my ferret mother, let alone my human mother.  I'll only be good if
you show me love, not anger and bigger species bullying." (Quote straight
from the ferret's mouth.)
[Posted in FML issue 3826]