It isn't that libertarians are pro-immorality, but rather they are pro-private property and against the initiation of force.
Respect for private property is the foundation of civilization, and hence why communism is the antithesis of civilized society. Communism is social disintegration.
Any libertarian worth his salt is guided by these two overarching principles. His stance on various issues is the result of being consistent to these two ideas.
That is libertarianism as I see it; it's nothing exceptionally radical.
Best explanation so far.