I have yet to figure out Grasshopper's "people gauge". She wrapped herself around the legs of a co-worker who is a little afraid of cats, and hissed at a dedicated cat lover. She would hiss at Dadcat's beer-breath when he used to drink it, yet would go all "cute cat" for our neighbor, Rafael, when he would pop in after a few beers in the evening! One good thing, she turned my coworker into my friend, and now Linda always asks about her when we visit!! It's definitely a personal thing, but what it's based in, only the cat knows!