A Pigovian tax (also spelled Pigouvian tax) is a tax levied on any market activity that generates negative externalities (costs not internalized in the market price). The tax is intended to correct an inefficient market outcome, and does so by being set equal to the social cost of the negative externalities. In the presence of negative externalities, the social cost of a market activity is not covered by the private cost of the activity. In such a case, the market outcome is not efficient and may lead to over-consumption of the product. An often-cited example of such an externality is environmental pollution.

Pigouvian or sin taxes are placed on goods that? Let's have some stream of consciousness first.
To answer the question, consider the following: A Pigovian tax (also spelled Pigouvian tax) is a tax levied on any market activity that generates negative externalities (costs not internalized in the market price). So, the answer is any market activity that generates negative externalities ( costs not internalized in the market price ).