  We report on the phase formation and the superconducting properties in the
NbS$_2$ system. Specifically, we have performed a series of standardized
solid-state syntheses in this system, which allow us to establish a
comprehensive synthesis map for the formation of the two polytypes 2H-NbS$_2$
and 3R-NbS$_2$, respectively. We show that the identification of two polytypes
by means of X-ray diffraction is not always unambiguous. Our physical property
measurements on a phase-pure sample of 3R-NbS$_2$, on a phase-pure sample of
2H-NbS$_2$, and a mixed phase sample confirm earlier reports that 2H-NbS$_2$ is
a bulk superconductor and that 3R-NbS$_2$ is not a superconductor above $T =$
1.75 K. Our results clearly show that specific heat measurements, as true bulk
measurements, are crucial for the identification of superconducting materials
in this and related systems. Our results indicate that for the investigation of
van-der-Waals materials great care has to be taken on choosing the synthesis
conditions for obtaining phase pure samples.
