Okay to dislike someone who hasn't done anything overtly mean?

I *seem* (operative word) to be very good at picking up subtle hints about personalities. I know someone who is sugary sweet, but I've noticed in the way she talks to other people that she tends to be self-centered, she subtly slants things to make other people look bad, and has a sort of caring, patronizing condescention. Everyone seems to think she's just the sweetest person, but I trust my judgement. Is it wrong of me to dislike her and mistrust her motives even though she's done nothing overtly wrong to me?