Scientific Socialism, folks:

The Communist Manifesto:

"The bourgeoisie, wherever it has got the upper hand, has put an end to all feudal, patriarchal, idyllic [?] relations. It has pitilessly torn asunder the motley feudal ties that bound man to his "natural superiors", and has left no other nexus between people than naked self-interest, than callous "cash payment". It has drowned out the most heavenly ecstacies of religious fervor, of chivalrous enthusiasm, of philistine sentimentalism, in the icy water of egotistical calculation. It has resolved personal worth into exchange value, and in place of the numberless indefeasible chartered freedoms, has set up that single, unconscionable freedom -- Free Trade. In one word, for exploitation, veiled by religious and political illusions, it has substituted naked, shameless, direct, brutal exploitation."

If there's nothing morally wrong with exploitation, how can it be bad? I suppose it could be economically inefficient, but then, why would the bourgeoisie want to do it?