Marxism is a method of analysis, it doesn't have leaders or corruption. Generally when anyone speaks about this, they mean that the Eastern bloc was full of corruption, I'm pretty sure that everyone in this forum acknowledges that. Just don't listen to them, they advocate the great man theory. Just read, read Marx, read revleft, and read Lenin. There is no point to rehabilitate the Soviet Union or "really existing socialism". Don't speak to the emotionalists about it, instead speak to them about the reality of capitalism and what a massive shithole it is for almost all of us.
“How in the hell could a man enjoy being awakened at 6:30 a.m. by an alarm clock, leap out of bed, dress, force-feed, shit, piss, brush teeth and hair, and fight traffic to get to a place where essentially you made lots of money for somebody else and were asked to be grateful for the opportunity to do so?” Charles Bukowski, Factotum
"In our glorious fight for civil rights, we must guard against being fooled by false slogans, as 'right-to-work.' It provides no 'rights' and no 'works.' Its purpose is to destroy labor unions and the freedom of collective bargaining... We demand this fraud be stopped." MLK
-fka Redbrother