Adrian Piper claims that we errantly fetishize art objects if we see them as unique, their spatio-temporal locations and histories not amounting to a full-fledged "identity, and their putative power to influence us a mere reflection of our own displaced capacities. Human beings, that is, are alone inherently creative, "alive," and non-reproducible.
Her complaint with fetishism is Marxist in spirit (as he applies the concept to commodities and economic "laws"). But the impulse to fetishize in aesthetics (as in human sexuality and religion), while clearly an epistemological and metaphysical error (the object of our fetish does not in fact possess the properties we ascribe to it), is relatively harmless. We oftentimes willingly submit to exaggerated or false accounts of the nature of art objects in order fully to appreciate their aesthetic dimension. (We "lose" ourselves in a novel, for example, tacitly attributing to its characters and setting more reality and power than they possess.)
It may be that Piper would not count these as legitimate examples of fetishism in art (because we are at least partly aware of our impulse to fetishize). At any rate, the very idea of fetishism seems to lose much of its force when transferred from the life-and-death realm of political economy to the highly subjective world of art.