I have used a different method to teach my ferrets to control their biting.
I permit controlled "play bites," but it probably will work to extinguish
biting totally.
 
Rather than flicking them (although I like the covered nostril variation), I
pinch them on the hindquarters or scruff of the neck.   Even the most
persistent biters learn pretty quickly that we top the pecking order.
 
My rationale - 1)  It is easy to control the pressure and duration so the
response can be varied with the situation.  Repeated bites get a longer and
harder pinch, for example, as do hits in areas that are no-bite zones.  2)
They do not learn that a quick moving hand is a potential threat and don't
develop a fear response to it (bite or run).  3) It mimics the way that
ferrets teach each other how hard a bite is acceptable. 4) They have to
switch mentally from offense to defense to get rid of the pinch.  5) It
doesn't require the precise targeting and timing that flicking does.  6) We
always win.
 
It works well for us and it may for you too.  It doesn't seem to teach them
to do a quick bite and run.  A lick, lick, bite pattern lets you set up for
a instant response to the bite.  You may find them adding more licks before
the bite until they quit biting altogether and just lick.  One of mine
favored the inside of the elbow for this, but now he is just a kisser.
 Also, a light pinch when petting will start gentle wrestling, I doubt a
light flick would do the same for those disciplined that way.
 
         Till next time.........Rudy the ferlosopher
[Posted in FML issue 1149]