In Vietnam, slave labor makes t-shirts sold in American walmarts. Is this successful or meaningful leftism?

The parent was asking about political parties. In Vietnam, the leftist party runs the country. If "in charge of a politically stable, economically growing country for decades" doesn't meet the definitions of "successful or meaningful" in the context of a political party you're going to have to be more specific.

More successful than meaningful, like the way China is nominally communist but arguably not meaningfully so, as he mentioned.

> Worker's Party is a center-left party that is currently the ruling partying Brazil.

PT stopped being a left-wing party decades ago. The current vice president was once a presidential candidate and leader of a neoliberal party.