I work with old people in nursing homes and assisted living facilities. I've had plenty of people who have dementia curse my name and become combative. They aren't really consciously doing it though.
However in high school there was an art teacher that hated my guts for a reason I couldn't understand. I took a few art electives but never had him as a teacher but I would often stay after school to work on projects. He always criticized my work without offering anything constructive and one day after school when I was talking with a classmate he told me to shut up. I had also lost my glasses one day and the last place I remember wearing them was in one of the art classrooms. I went back to ask the next class if they had seen them and before I could finish my sentence he said, "Nobody has seen your glasses, now get out."
.....I found them in the hallway right outside the room cracked in half later on that day. I always wondered if he had actually found them and broke them on purpose.
They can be rude but it never offended me as most of them have lost their faculties 
