Hi Sean,
I have to second the idea that if you've managed four interviews you're doing something right, and it's probably just a matter of time before you get your berth.
On the enthusiasm front, that makes me consider the idea that an interview is (or can be) a two-way thing; you're checking them out as much as they are evaluating you, and by the sounds of things that wouldn't have been the place for you anyway; would you have wanted to work with your head constantly bouncing off brick walls?
I have interviewed people twice in the last three years, as we have had a team expansion, and we now have to replace a member who is leaving for warmer climes, so I'm interviewing again next week. One thing I have to say, even though it's not directly relevant to interview, is that if an employer asks for particular experience, in the current employers market they almost certainly mean it. We had over fifty applicants, of which fewer than 10 have relevant experience. OK, it may be worth chancing it, but the odds right now aren't good, and no matter how much people say 'safety is safety', in my opinion that isn't necessarily true. I know very little about shoring up excavations, how many people on this forum know about the risks associated with clinical beds?
Now if we were still in a period of full employment I might be prepared to chance it, but right now I can pick candidates who, I feel, would drop right in. I might be wrong, there's still an interview to go through, but on paper I can shortlist people who fit the spec entirely.
At interview I certainly don't look for a 'firm handshake'; this isn't the masons, and I couldn't care less about grip strength. I look for enthusiasm, a positive approach to the interview, knowledge of the subject and evidence that the interviewee has taken time to prepare; that they know somthing about this organisation and the work it does, and that they have considered the presentation topic in some depth and taken time to research it. After all, what's on offer is a long-term commitment, so I expect a commensurate degree of preparation,
John