A good actor can act as a bad actor,
to the extent that you believe that
(1) he or she is really a bad actor,
(2) he or she is can never ever be(come) a good actor, or
(3) he or she is not acting at all.
Paradoxically then,
the best actors can be the worst actors,
who might never be identified.
(A bad actor cannot act as a good actor though).