It is hard to say how the ancients judged each other, but quick judgment of our fellows is surely a contemporary American weakness. Those who quickly place others in simplistic categories, never hence to remove them regardless of whatever new evidence may be found, should do something that no doubt few do anymore: read Montaigne. He notes in one:
Consultation and deliberation is the beginning of all virtue, and constancie the end and perfection. [Essayes of Montaigne, Vol. III, Tr. John Florio, Ed. Justin Huntly McCarthy (David Stott: London, 1890), 4.]
But do not imagine the relatively modern Montaigne was the one who came up with this gem of an insight: he himself credits it to Demosthenes. Much has long been understood that today seems incomprehensible to almost everyone.
Noting numerous historical examples of unpredictable shifts of temperament, Montaigne warns that “to judge a man, we must a long time follow, and very curiously marke his steps.”  He implies that almost anything is possible with almost anyone, so superficial is the reasoning by which we wander through our lives. “No winde makes for him that hath no intended porte to saile unto.” 
So let no short-sighted, long-winded politician tell you who is good in this world and who is evil. More often than not, it depends.
My apologies to readers who wonder why I am quoting old-fashioned English rather than the old-fashioned French in which Montaigne wrote. Simply, that’s the book passed down from some unknown relative I happened to chance across on my bookshelf. Someone send me the original French…