It's the same mechanism. When you say "Actually Iran/Cuba/Venezuala/China/other place the US wants to starve and/or bomb is bad", you're just carrying water for imperialism. It's genuinely more harmful than when the right tries to justify those actions because it tricks people who would otherwise support those people into supporting hostile actions against them in the name of opposing their government.
The grossest part is that the people making these assertions never know what they're talking about and genuinely don't care beyond its utility as hostile evidence. Showing some lemmitor who thinks Cuba hates gays or isn't democratic their latest constitution doesn't shock them that they've been mislead and result in any change in position, instead they just forget that bit of trivia and move on, sure they're helping somebody by supporting America's hostile actions against them.