I've had a couple say things to me like "They're definitely going to want to vote on you," and "that is the best answer you possibly could have given to that question" (at a school I later got into), and also, at another school, the interviewer said "You are going to be admitted." But I've also had some interviewers just sit there and look stern, like at Arizona. I haven't gotten enough acceptances/rejections yet to see whether that's actually reflective of whether I get in.