Not necessarily a good one, though...
It seems that a narcissistically driven person has difficulty knowing when they are going "over the top". They seem to over-do everything so much that you often get the feeling like they are acting. Your intuition that they are acting is exactly what you are witnessing. As Dr. Hare describes the narcissist/psychopath: he knows the words to the song, but not the music. They learn what emotions people normally express in certain situations but they don't feel those emotions themselves. The result is that you end up watching their performance and sensing a certain hollowness. It doesn't ring true. Even when witnessing a narcissistic rage you may have sensed the acting job. True rage isn't like a spigot that you can turn on and off. A normal person experiencing rage has a hard time settling down. They have to work on calming themselves. Let a narcissist rage and then the phone rings or another person walks in the room....BAM....they are transformed. In an instant the rage is replaced by a smile. Normal conversation ensues. Crazy-making if you are a witness and victim of this behavior. So, even the rage is manufactured. The desired outcome is control of you. It is one of the more effective tools in the narcissist's kit designed for a certain effect.
I am convinced that the narcissist is only a moderately good actor. The signs of the falsity are always there, but we often are susceptible to believing the act because of weaknesses in our own selves. The narcissist has a very sensitive detector of the weaknesses and faults of humanity; they hone in on yours with great precision. These weaknesses make you vulnerable to exploitation. We often believe lies because we want to believe the lie is truth. It is imperative that we be brutally honest with ourselves about ourselves. It is more important to know yourself than it is to know the con-artist. If you have acknowledged your weak spots you'll guard them more carefully. You'll be attuned to a person who has honed right in on those weak spots. You'll listen to the alarm bells and wait for more information before you act on the promises, flattery, proffers of riches or love of a possible narcissist/con man.
Pay attention to the disconnects, the non-sequituers, the contradictions, those moments when you wonder if you are imagining things or going crazy. Something is wrong if you consistently get these feelings. Stand back. Know what you know. Don't let the possible con-man's persuasive arguments fool you as he tries to get you to un-know what you saw with your own eyes and heard with your own ears. This will allow you to hold on to what is truth making it much less likely that you'll believe a lie. Narcissists are actors. They are trying to shape you into playing your part in their play. Beware. Know thyself.