But isn't it our obligation as conveyors of knowledge through
material culture to show all aspects of heritage - even if they are
obtained in a suspicious manner.

For example, recently a list of 10,000 paintings that were sold by
the nazi's in the 30's has come to light. A lot of these are assumed
to have been stolen from - among other cultures - the Jews. One of
these is a very famous painting called the Screaming Lady (i think
that's its title). The Tate Gallery in London purchased that painting
from the nazis. Now we know it is of dubious origin, but we have no
way of knowing who the original owner was. ICOM states that this is
illicit, and should therefore not be exhibited. Why not? If not
shown, it will be hidden from public view. A great waste of a
valuable and important artefact.
I suggest that ICOM is too rigid in its application of moral ethics
to society, and that in examples such as this, a different approach
must be undertaken.

-Simon Clark