The only common thread I've noticed is that it always refers to an imperial core person admiring something foreign. You're somehow not a tankie if you're actually from China and you're a Marxist-Leninist. In that case you're just an authoritarian. But if you're from Canada and you say nice things about China? Then you're a tankie.

There's some kind of nationalist brainworm built into the term. There's some kind of conception that foreigners just do socialism incorrectly, but white people can do it properly through...I don't know, voting every 4 years, or begging for it nicely or making a utopian settlement in the woods. But if you're a white person who wants revolutionary socialism, you've allowed scary foreign devils to pollute your mind and you're a tankie now. Telling liberals that being a "tankie" is the overwhelmingly most normal position for communists worldwide shortcircuits their brains. They can only conceive of three types of communists: Idiot white teenagers from imperialist countries, cynical dictators, and brainwashed foreigners who can't think properly because they're foreign.

Way too many times I've been talking with someone who called me a tankie, and I ask them why it seems like China and Vietnam have such high approval for their respective states. That's when it starts coming out. They'll say communism is just a better fit for their culture, or that the people there are more easily brainwashed, or that the approval ratings are all lies. It's so racist and disgusting.