Anticommunism is a morality tale. They are wicked, we are good.
The “we are good” part is usually left unstated. It is simply taken as self-evident. This makes the assumption all that more powerful (and preserves it from challenge).
But if the anticommunist is forced to concede that the West, the Free World, has done something terrible, committed horrible crimes, there are nevertheless an infinite number of excuses.
Here is one: “This is shameful. We failed to live up to our own standards.”
Do you see what’s going on? We, the good guys, have these elevated standards. They represent our true selves. We don’t always live up to them, but nonetheless they represent what we really are. They show how good we are: we have such high standards that we must sometimes flog ourselves for not attaining them perfectly.
Now compare this to communism. When do you ever hear of communism being criticized for not living up to its ideals? Much more often, communist ideals are either mocked as ridiculous or condemned as cynical ploys. With communism, it is the crimes (real or imagined) that are the real reality of communism. All else is propaganda.
With us, it is our ideals that are the real reality. All else is, at worst, a failure to live up to our ideals.