No,merely the realization that human nature (free will, for those of you more religiously inclined) makes "true" socialism (of the sort envisioned by most of these nuts) impossible.
There will be some willing to make the sacrfices necessary, obviously, but more often than not, those sacrifices will have to be coerced from the vast majority.
And which/what bad history are you talking about?
Too much doctrinaire mish mash for me.