I agree that INFJs have a facade of more gentility and when roused, our resentment can be striking. Devastating, even.

Most of the time, I seem very somber/moody, and that supposedly makes me seem innocent, how quiet and sad I seem. I tell you, whoever said “Their faces convey the feeling that their soul is suffering even when it is not” knew their INFJs! People have asked me out of the blue if I am okay, I seem down today, or I’m very quiet and I look like I’m on the verge of tears when I’m just merrily contemplating life in my own bubble.
People do react with shock when I get ugly. I had an ESTP doubt me when I mentioned I have quite the dark streak, but that was out of her competitive nature, I think. I can shrivel anyone under my glare… I can go from an altruist to a contemptful bitch in the beat of an insect’s wing…

… Oh, sorry. Yes- to the OP’s question: I have been told I am intimidating or scary many times.