I've never faked being hurt, but my two labs seem to know when I'm sad or not feeling well. They come up to me and lay their heads on me, especially my female. She's very perceptive. I've often wondered what she'd do if somebody tried to hurt me, but I hope I never have to find out.
Years ago my brother had a family member visiting, and in the middle of the night his dog jumped on his bed and began to harrass him and his wife. They told him to go away (he was a very obedient dog), but he was persistent. When they finally got up to see what his problem was, they found their visitor having a heart attack in the living room. The doctor said that she probably would have died if the dog hadn't woken them up to help.