We get sucked into an enjoyable conversation about the particular niche of tech that we both happen to be in and we start exchanging war stories.

I move into sell mode and also ask explicit questions of what other jobs they are looking at and where they are in the process.

I try to be neutral. It's a team decision

i find this fairly easy to read from their body language and faces. Lots of smiles, relaxed body language, as the interview goes on it evolves from the Q&A to more of a mutual, free flowing conversation. Gender also plays a role. I am a woman and if my interviewer is a man, i have been 100% right about predicting the outcome: if I come out of the interview feeling that he "liked" me, i know this is vague, but it's the same feeling you get if you know a first date went well, I have always got the job. With female interviewers occasionally I have been wrong.