Actually, I always called my political orientation "I would be communist if I didn't know people better".
Being rather left on the spectrum, I'm honestly not at all opposed to the ideal goals of communism; but there's one problem - it's based on the completely wrong assumption that people can all suddenly become rational and respectful of each other as much as themselves.
In this sense, those who created the US constitution were way ahead of Marx and the crew. They certainly realized the failings of humans, and created a much more reliable and stable system. Neither, of course, is unexploitable.
Communism never existed, by the way. China and the USSR, and all those other states, are/were just examples of how to take an ideology and exploit it to one's own ends. Likewise, the idea of "democracy" has already gone through the wash in Russia and was/is likewise exploited by the government there.
People who haven't been screwed by their government really shouldn't take it for granted. As long as there's people who want to be better than others, communism will never work, and I think that's something that's programmed into human nature (not to say inherent to everyone) and has driven society as much as it has driven natural evolution. Liberalism, in the end, is just far more appealing to most people - at least on a practical, everyday level.
Anyway, I won't take this for an opportunity to preach my dreams of "rational socialism"
