>>And too many folks are afraid to offend certain groups by acknowledging, even with eye contact, that they might be dangerous. <<
I don’t look them in the eye, I look at where their hands are positioned. Are their hands clenched or open and relaxed?
1.) I see you.
2.) I could describe you, and I could identify you.
3.) I'm not timid. I'm not even particularly nice.
4.) In fact, I'm making plans right now just in case.
That's been enough, so far, to deter any attackers (and I have lived/worked in some pretty questionable areas.) Most attackers, especially cowardly ones like this, are looking for the easiest possible prey.