Some present in the board appear to be successful and thriving. I would even go so far as to assert that a minority have striven in rebellion to their dysfunctional upbringing. Often the narcissist parent will put their offspring down, behaving as if permanently astride a pedestal of moral/social virtue: puncturing this falsehood becomes desirable to those who suffer under it.
I suppose in the NPA schema a bad narcissist parent is an individual who, for whatever reason, has ceased inverting their narcissism and instead broadcasts self-perceived superiority via ridicule or posturing with tedious and repellent regularity. This is just one subset or symptom of the overall problem though!