popa bar abba.
I agree.
I also think that what shlishi said is right, that unfortunately some people who seem to excel at bain adam l’makom neglect bain adam l’chaveiro, and this gives fodder to those who do the reverse to expand it to an entire group. It’s a kind of defense mechanism.
Regarding treating all human beings with respect, I know of a certain rosh hayeshiva, a gadol, who complimented the janitor, while not in his presence. One of his talmidim asked why it’s not lo s’chaneim, to which he responded that one must always speak positively, to train ourselves to be positive. Otherwise a negative attitude will come out at the wrong time.