Jeff Hunter discusses a model for thinking about job search transactions and the roles involved.
One thing I will add, at least as it relates to my position, is that it's good to understand when the value transaction has taken place. I receive many requests from candidates that want to discuss their backgrounds, get interviewing tips, have lunch (some can be quite persistent!). This always seems to be after I have forwarded their resume along to the appropriate line recruiters. At that point, the value exchange has taken place; they get their resume in front of the right recruiter, I'm able to provide some value to the line recruiters by providing resumes that match their open roles. Not being a line recruiter for any of the jobs, there's no incremental value-add achieved by additional meetings between me and the candidate. That may sound a little harsh, but if the recruiters feel that they have a role for the candidate, they will be more than happy to spend some time on the phone with the candidate (they want to). But given the number of resumes we receive, we really have to spend the time where we feel we have a potential match.
I always feel a little bad saying no to peoples' requests to meet. I love helping people with career advice via the blog and e-mail when I can, but if I said yes to these requests to meet, I'd be a career counselor and I'd be charging by the hour. I have to balance goodwill activities and actually getting my job done. So I've made a policy of saying no to these requests to meet (because how would you decide which requests to say yes to?). Plus I think I've been pretty giving of my career advice on the blog.
Anyway, it's just something to think about when engaging with a company you would like to work for. If you contact me to meet and I say no, it's not because we don't appreciate your interest.