  Exact solution of the Ising model on the simple cubic lattice is one of the
long-standing open problems in rigorous statistical mechanics. Indeed, it is
generally believed that settling it would constitute a methodological
breakthrough, fomenting great prospects for further application, similarly to
what happened when Lars Onsager solved the two dimensional model eighty years
ago. Hence, there have been many attempts to find analytic expressions for the
exact partition function $Z$, but all such attempts have failed due to
unavoidable conceptual or mathematical obstructions. Given the importance of
this simple yet paradigmatic model, here we set out clear-cut criteria for any
claimed exact expression for $Z$ to be minimally plausible. Specifically, we
present six necessary -- but not sufficient -- conditions that $Z$ must
satisfy. These criteria will allow very quick plausibility checks of future
claims. As illustrative examples, we discuss previous mistaken ``solutions,''
unveiling their shortcomings.
