  This paper discusses the Monte Carlo and Molecular Dynamics methods. Both
methods are, in principle, simple. However, simple does not mean risk-free. In
the literature, many of the pitfalls in the field are mentioned, but usually as
a footnote - and these footnotes are scattered over many papers. The present
paper focuses on the `dark side' of simulation: it is one big footnote. I
should stress that `dark', in this context, has no negative moral implication.
It just means: under-exposed.
