The kind that thinks communism is the same as nazism and thinks communism is when the government does things.
I hate liberal brain worms.
They seriously do as much damage to the left as fascists by punching to the left and spreading capitalist anti-left propaganda. They overall weaken leftism and help fascism.
We need more left unity, folks. Fash ain't gonna bash themselves. 
It's almost impossible, their narrative that the tankies are all genocidal is almost a universal, unshakeable truth to them. There is the rare occasion that when they're given the facts on a very specific instance they change their mind, but it's not easy.
Yeah i think with these kinds, it takes something very specific in order to have a breakthrough. Best case that leads them to a wider understanding and radicalizing, but frustratingly for many of those libs that's where it stops.
Its insteresting to see NATO supporting western "leftists" have like maybe one or two AES they support and know the propaganda is wrong about (usually Cuba or Vietnam, probably because of the US involvement in obstructing both countries)