Socialism was a good idea, maybe an unrealistic one in many respects.
Whereas Communism via "Vanguard-party" was always a bad idea. Pretty much all of communist countries never got past the Vanguard transitional stage and ended up with a brutal dictatorship.
I think socialism has worked pretty well in the UK, all things considered. We've never gone the whole hog, but we have had a welfare state and a number of industries nationalised at various times. I rather like having a mixed economy where some elements of capitalism are balanced by socialism.
I'm not sure how this meme started, Communism is a `terrible` idea. The goals of Communism are good but the actual plan might be the worst model of government ever tried.
[1] - http://en.wikipedia.org/wiki/Communism