I have never, as in the well known Chorus Line song, scored people numerically during an audition. I'm a pretty organized person, I like margins and discipline as much as the next guy, but somehow I can't just assign an audition result like it was an SAT score. I almost wish I could. It would be easier sometimes to just pick the highest score than to factor in all the variables. (Hmm, she's in the 90th percentile for vocal ability and the 75th for tap dancing ...)
I have conducted auditions where I’ve made detailed notes about each person, and others where I’ve just waited to see who made the best overall impression. Sometimes, it is obvious. There is one person who fits what I have in mind (or brings something even better than what I’d envisioned), who I am confident will come through with flying colors. Their talent stands out, they are the one who I can picture in the role and I am comfortable signing them up on the spot.
When there are two or three who could each handle the role, that’s great – options! But that’s also when the intangibles become more important. They are the factors that have less to do with talent and more to do with personality and your personal track record. There are so many considerations that influence the decision, sometimes in very subtle ways.
People who have worked with me before have a leg up - assuming the prior experience was positive. That's only natural, and one reason to be willing to accept a small role with a new director. When I know what someone has brought to the table in the past, I can decide if I want that to show up on the new table I'm preparing. These qualities, good or bad, can be tie breakers when all other abilities seem equal.
Never discount your behavior and attitude at the theater as being unimportant to your place in the next show. Right or wrong, it is often about more than just who is the most talented. I have seen people with lesser ability perform quite successfully on stage, and been happy with the outcome because they helped to make the whole experience better for the group. I would choose those people again, and sometimes find myself looking for a way to include someone who I just really want to have around.