I'm curious, what are the "good" methods for discerning/filtering quality of people? How are "good" and "bad" quality of people categorized? (binary? spectrum/distribution?) How can you estimate/measure the quality of the filter/method with precision?

I assume no filter is perfect and mistakenly filter out "good" quality people too, so if this method isn't good that suggest there's a metric and a more efficient method out there. In your personal experience what worked better?