I think what the discussion around "narcissism" and "shamelessness" in recent years (apparently occasioned by the rise of Trump) consistently misses is that narcissism as understood by psychologists isn't characterized by lack of, or imperviousness to, shame; rather, the narcissist's acute and formative experience of shame is thought to be at the very core of the disorder, with the subject's pathological behaviors all aimed at suppressing or hiding that emotion.
This is accurate in my experience, coming from an unloving household where shame was the name of the game.
My coping mechanism became to ignore shame and shaming attempts, first in defiance, later "on principle", at any cost (so what if I don't get that toy I always wanted, I won't be manipulated in this way). Obviously this has caused some social problems in adulthood, as I struggle to be critical to myself and others without invoking feelings of shame. Or give a friendly advice without thinking I will hurt someones feelings (because they are doing it "wrong").
That said, I'm not sure whether the distinction matters in practice. It's certainly frustrating for my friends who can't playfully shame me into action, without me becoming all fight/flight, pretending to be oblivious, or outright ignoring them for months after...
I'm lucky enough to have found friends and (other) family that taught me positive reinforcement and nonviolent communication, as I'm seemingly incapable of handling negative feedback (at least openly).
These things can often be a mirror image / opposites of each other -- like for example people with abandonment issues can often sabotage relationships by abandoning their partners. Seems counter-intuitive but it makes perfect sense once we see the fear that drives it, and the coping mechanism of "I will abandon you so you cannot abandon me".
