So, when you're walking through the streets and people are saying hello to you and aren't in the friendlies of moods, do you say hello back cheerfully

nope, i'm normally quite aloof and standoffish.

Yup. If someone is going to make the effort, it would be wrong to let my mood take away from their kind act. Maybe it was hard for them to do that. Maybe they had to rise above their own mood. I think responding to a kind word is part of being human.

Yes