I believe that there is an alternate world where Trotsky and Stalin had the same beliefs they do in this one, but the luck of the draw meant that Trotsky ruled Russia and Stalin got an ax in the head. There, I am sure, some of the nicest people around sincerely believe that it was not Marx's theories that killed tens of millions, it was Trotskyism: a vicious, bloodthirsty perversion of Marx.
In other words, "Stalinism" is a euphemism used for Communism when it gets caught killing millions of people at a time. We now know that Mao and Pol Pot also had at least seven-figure body counts (and many other Communist regimes went through a briefer phase where they were executing at a rate that would embarrass Texas), and the third time is enemy action, or a tradition, or at least something that suggests that maybe it's time to ask why this wonderful idealistic system somehow keeps handing the reins to megamurderers.
Back in the '50s the unspeakable Roy Cohn insisted that he was a liberal anticommunist. There was some feeling that this self-definition was as deluded (and in fact oxymoronic) as his less publicized belief that he was a real he-man who just happened to enjoy taking it up the butt from other real he-men. Still, I now think of myself as a liberal anticommunist (and I neither think of myself as a real he-man nor take it up the butt).
For one thing, Cohn's methods were hardly liberal. I think fundamentalism is a Bad Thing--a corrupt thought system used by evil people to bewitch stupid people and harm innocent people--to the extent where I could reasonably be called an antifundamentalist, but I don't want to have fundamentalists fired from their jobs, called before committees to snitch on their friends, etc.
[It's an interesting thought, though. HUAC asking, "Are you now or have you ever been a fundamentalist?" The big showbiz probe would no doubt center on country music. I can hear it now: Johnny Cash refused to name names, but George Jones, as the Russians phrase it, "cracked like a hymen." And there would be hostile witnesses: "Mr. Dickens, the next time you ask the Bird of Paradise to fly up the Committee's nose, you will be cited for contempt."]
If this sort of thing had taken place, "liberal anti-fundamentalist" would be a term people tried to avoid, and liberals would probably have been more circumspect in condemning Jerry Falwell's lunacy about the real reasons for 9/11.
Besides, Cohn was a premature anticommunist.
We know that some people who opposed the Nazis and other bad guys in the '30s were later stigmatized as premature antifascists. One can say that it is unfortunate that some people were caught in a culture or time period that was unreasonably prejudiced against them; Big Bill Tilden and Newton Arvin could be described as prematurely gay. But the premature antifascists suffered an even more unjust fate: They were be punished specifically for being right too soon. To a science-fiction person like me, that's particularly offensive.
And yet one notices some interesting things about premature antifascists. For one thing, a significant subgroup of them started out thinking Hitler was awful, then decided he wasn't all that bad as soon as he signed a treaty with Stalin, only to go back to antifascism when Hitler and Stalin were no longer buddies. One is tempted to attribute to this subgroup something more than excessive prescience, perhaps to suggest that some of those who thought fascism bad only because it was anticommunist were less prophets than blind pigs finding their proverbial acorn. (Arno Karlen's Why Did the Skies Not Darken? comes close to suggesting that Hitler's real evil was trying to wipe out the communists, but the Jews somehow got in the way. I suppose this is not true Holocaust denial, but it ain't good.) Of course, many of the premature antifascists really did perceive the evils of fascism before they became obvious to the rest of us, but we should at least ask what sort of antifascist they were (something both sides have resisted doing).
In the 1950s, it was possible to believe in Stalinism, to believe that the Marxist program had been perverted by a bad individual. (Marxism itself tends to deny that individuals have that kind of power, but let that pass.) There were people who hated communism because it supported peace or integration, as well as those who had better reasons, and the first group (which Roy Cohn did not belong to) could certainly be called premature anticommunists.