One of the first pieces of work I ever published - or, to be precise, the second - was on the subject of commodity fetishism in the thought of Karl Marx. I could not then have imagined that a letter would one day appear in the Times, saying (£):
We must continue to work to reduce alienation and think more about the effects of commodity fetishism.
The context suggests that the author of the letter may mean by commodity fetishism something like an avidity, or possibly even greed, for the products produced and sold in capitalist markets. This is not, however, what Marx had in mind, though it may be indirectly connected with what he had in mind. It is more complicated than can be adequately laid out in a short blog post. The article I wrote in 1969 in which I tried to explain it is available here (£) and here (without £); but, in a nutshell, by the fetishism of commodities Marx meant that under capitalism produced objects acquire social properties (values) which appear to belong to them naturally, and that these appearances - which are real and not illusory - obscure from view the underlying economic relations of which they are the product. One element of these real but misleading appearances is that the relationship between capitalist and worker is an exploitative one but appears to be fair or just.
It is relevant to add that, whatever insights Marx's theory of commodity fetishism may relay, it is associated with a conception of (economic) value that is inherently flawed.