Research methods and job ads

I'm writing up a job ad for a vacant position in my department today. I've been thinking about the skills and qualifications that I'm looking for and it occurs to me that one of the things that makes hiring difficult is that we (I) typically don't think much about how I'll measure the qualities that I'm looking for in a new employee. For instance, if I say that I'm looking for someone who is self-motivated and has a positive attitude, how will I determine whether my applicants have those qualities? That's not a question I would have asked myself before I started learning about research methods.

Before, I would have probably tried to come up with some way to quantify things like supervisory experience and familiarity with Windows Office software which are fairly easily quantified into measurements that have an ordinal relationship. But I would also have tried to quantify things like self-motivation and positive attitude which I think is much more difficult, not to mention subjective. This time I'd like to take a more qualitative approach to analyzing resumes, applications, reference letters and interviews (and helping the members of my search committee to do the same).