When you vet someone for whether you can be close friends with them, what's a seemingly unimpactful characteristic about someone that would instantly rule them out as a potential close friend for you?
I take "unimpactful" here as being oblivious are aloof to others. You don't have to be an asshole to treat someone poorly. That just requires not thinking of anyone but yourself, which is done by assholes, but can also be less severe and merely lacking compassion for someone because they're here to do a job and not a person.
When somebody manages to actively be an asshole to random strangers they just met it's actually kind of spectacular. Usually people can mask up at least a bit in public.