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It's not impossible in every respect, and certainly it's methods of institutions in the past were heavily influence by the level of social and technological development of the countries that attempted them: For instance, Russia can't do democracy correctly NOW, so what makes us think they were doing communism correctly THEN. Besides, every country where Communism was attempted went into it directly from an agrarian semi-feudalist state, full of serfs and and with no prior existing "means of material production" to share common ownership, except for the land. They had no pre-existing structures for creating wealth, like the developed countries have/had, so they were left with the proposition of trying to build it from nothing.
Back to the point about it not being impossible for everything, take a look at the way piracy and legit free-software operates on the internet. With no material cost for the REproduction of these goods, we essentially share communal ownership of all freely availible software, music, and movies already, whether the laws agree or not. As piracy moves towards 100%, it would increasingly resemble normal software distribution under a technologically developed free Communist state. The loss of the profit motive would certainly detract to some degree or another from the production of new media, such as music, films, and games, but think of the wonder of having free and legal access to every single creative work ever produced by human kind...
A possibility under a sufficiently developed Communist state.
Throw in automated factory production, nanite controlled garbage disposal, a renewable energy source, and a few other currently-sci-fi ideas that would substantially decrease or elliminate certain material scarcities along with the need for human labor, and you have the grounds for a workable Communism that has neither shortages, nor garbage men and sewer workers recieving the same rewards as research scientists and brain surgeons.