I was never diagnosed with narcissistic personality disorder or any other secondary disorders when I was tested because for some reason, maybe because I'm "intelligent" the psychologists wanted a full profile on me, so I had to undergo hours of testing to come up with the PTSD diagnosis (which myself and my therapist had already confirmed).
Anyway, if I were confronted with the question about my soul, I'd likely answer in jest that I had none because I'd immediately recognize it as a probing tool that someone was trying to use on me to "classify" me. I'm not keen on people trying to classify one another outside of a clinical setting and without the proper training. That being said, I know post trauma how wary people become of others, I keep my distance because to me people in general are just objects waiting to smash into one another and the aftermath of that would place me in a horrible spot. So that is my self protective defense.
I do agree with Anthony though, people can score high on narcissistic traits but not meet the criteria for NPD or other anti-social disorders. Just because someone is narcissistic does not mean that they necessarily have a disorder of their personality and because we can't test them, we have to rely on ourselves to know what is good for us and what can harm us. There is no, to paraphrase Hannibal Lecter, "blunt tool" with which we non-clinicians can use immediately identify when someone else is going to be good or not good for us, we have to rely upon our past learning experiences and trust our own judgement.
I'm not happy with all of these "Psychopathy Tests" and pseudo-psychological, hip pop-psychology websites that are popping up all over the internet, call me crazy but what is the obsession with identifying and classifying these types of people? So we can avoid them? To be honest, they won't avoid you and this is more the issue. I think it actually does more harm to the victims by feeding into their paranoia rather than fostering solid coping strategies and giving them reasons to not isolate.
One of my friends would likely score high on the narcissism scale, he likes to grand stand in crowds and when he's with me alone he can get very emotionally manipulative. I recognize this now and I will walk away before he gets the upper hand. I cut off his supply. This is my power over him, it's not the other way around...and I have PTSD, so there's proof that despite this fact, I can still "handle" him.