1) I like it when candidates show an interest in the less glamourous but more worthy aspects of the role e.g. developers who are interested in a rigorous software development life cycle (SDLC) - by this I mean they see testing as a key responsibility that THEY see as part of their work not something forced on them.

2) Candidates who are more interested in the role than the interviewer is with filling it. I find that if I have more enthusiasm to get that candidate into the job than the candidate has in coming to do they job then they don't want it enough.