In "Blink", Malcolm Gladwell talks about a study conducted where complete strangers were able to better identify personality traits of college students better than their own friends could by only looking at their dorm room.
This is my best friend Jane's dorm.
I've never met Jane before.
No, she's normally not this neat. She probably just made it look nice for you. She's definitely "Type B".
Her dorm looks really neat. She's definitely "Type A".
I'm "Type A".
Here we see how the complete stranger was able to identify characteristics about Jane's personality better than her own best friend