[Eomer] "How shall a man judge what to do in such times?" "As he ever has judged," said Aragorn. "Good and ill have not changed since yesteryear; nor are they one thing among Elves and Dwarves and another among Men. It is a man's part to discern them..."
We should not find it plausible that a character in Lord of the Rings was unable to discern good and ill; yet we somehow don't expect modern people to be able to do so. We let ourselves and other off too lightly: it is a man's part to do this. And if a man fails to do so, and supposes Sauron or Saruman to be good - he stands judged.
This would apply to those among the Easterlings, Dunlanders or the Haradrim; who were surrounded by willing servants of evil, and for whom expedience (a man's very life) depended on choosing evil... We would still expect a good man to know that he served evil with his sword; even when terrorised and enslaved.
Why then should we be keen to absolve the mass of Western men from a responsibility for knowing that the global establishment, national politicians and mass media are truly evil? Is it that They pretend to be good, and espouse noble ideals? So too did Sauron and Saruman.
But the servants of evil knew that they served evil, because it was to the evil in their hearts that S & S appealed.
All men have evil in their hearts ("The line dividing good and evil cuts through the heart of every human being" - Solzhenitsyn.) And that is indeed how we make a discernment - precisely because we each know both good and evil, and therefore can know which we serve, which of good or evil is active in our belief, motivation and actions. This we can and do know.
We can pretend that evil is good - that (for example) resentment, pride, fear, cowardice, lust, greed and despair are good - 'when properly considered'... But then we also know that we are lying to ourselves, and inverting true values for reasons of expediency.
We each know, and God knows that we know - no matter how cleverly we deny it to our-selves and to The World.
The responsibility for making a correct discernment is inescapable because the capacity of discernment is universal.