another perspective
I go the way of intuition and sensitivity. Shelties are highly intuitive, or mine have been. Mine have ALL have been very good judge of characters. If mine get unusually timid, nervous, or shy. I tune in to what is going on around them, and try to see it from their frame of reference. I could usually pinpoint the sudden reluctance or change of behavior. I would stop and take in the environmental cues, and 98% of the time they were highly aware of circumstances I would have missed and there were good reasons for their fear, apprehensions, etc.