Legitimate Grievance?

In a discussion this past week in our History of France class, the professor made some remark about how communism is a very "optimistic" belief system, regardless of its alleged flaws or positives.

Naturally, I couldn't stand such a small, seemingly "positive" comment being made about communism.... so I quickly raised my hand and said that communism might make people optimistic, but its borne out of a deep pessimism and distrust/bitterness with society.

Anyways, was my comment on-target or is communism, in its most pure sense, actually optimistic? Is calling communism "optimistic" an objective remark? Do communists still sincerely believe that their belief system would lead to anything positive at all? And since I can't imagine that they honestly do, how could their belief system be classified as optimistic?

Aren't all belief systems essentially "optimistic"? Nazism/Fascism seems the most optimistic of them all. Returning to a time of glory... purifying society... optimism for war, etc. etc. etc.

Oh and there's also an interesting discussion going on at Let It Bleed, on why the Swastika is way more detested than the hammer and sickle, and whether that should truly be the case. Oh and I'll also point to a post that the monger made a LONG time ago, where he states that he considers communism to be (very slightly) worse than Nazism. I can't say that I really agree with him, but I think it's worth a look nevertheless.