What the poster is saying is that most people equate Communism with its most flagrant upholder: Russia. Most Americans look at the worst stages of governments (a la Chairman Mao, Mussolini, Stalin, Hitler, etc.) as the only form of that government. That is what he means by saying that they are seen as 'Evil', since most people would say that these specific governments were Evil, making the government types themselves inherently evil...the power of ignorance en masse.
The problem with governments, however, isn't the government itself. Each type of government works beautifully on paper, and is perfect for its own reasons and needs. Communism and Socialism are two of the most perfect government types, but could never work out on a full scale the way a Republic or Democracy works. The problem? It goes right with this game - Elements...Human Elements. The human element is what essentially dooms any governmental system, with things such as greed, power, lust, corruption, etc. On small scales, any government type could possibly succeed, all that is needed is the coming together of the populace to a shared vision. On large scales, however, there is no shared vision, as everyone has their own wants, needs, and ideas. People are inherently too different for governments to be perfect, as not everyone can be pleased by everything that is done.