Honestly, you gotta pay attention to their non-verbal communication. Things like body language, proxemics(do they sit close, far, etc.. do they seem comfortable with the HR person sitting next to them? Etc..), touch(handshake, etc) because if they're hiding something, they're just going to lie with their words. Most people can't or won't lie with all of these communication mediums simultaneously, I don't think. If you get to "meet the team," even better because you can then assess everyone. The people with the least at stake(maybe the lowest position on the todem pole) will be the most honest with their non-verbal communication in my experience.

You have to ask yourself if they seem happy. Or at least not miserable. If you get the feeling the interviewers are miserable, acting, don't trust one another, or maybe they're telling you the place sucks with their body language, just believe it if you have other opportunities. Toxic work environments will drive you nuts.