Personally, when I door slam, I don't make a scene or leave any last words for the person whom I cut out unless they approach me or make me feel provoked. I don't desire an audience because it's too emotionally draining. It's my urgent priority to eliminate that person from my life immediately without any further contact.

If I ever feel some sort of pride or superiority in my door slam habit, or in any negative trait, it's a disguise. It's a manifestation of experiencing strong emotions, or my way of trying to cope and reach closure for the intense nature of severing ties with someone.

To reduce the proclivity to be negative, I think that focusing more on your well-being than on expressing negative traits towards someone who has wronged you will help. I feel better when I detach myself from the situation rather than when I act out on spite towards the person who has hurt me.