  Achieving high accuracy and precision in stellar parameter and chemical
composition determinations is challenging in massive star spectroscopy. On one
hand, the target selection for an unbiased sample build-up is complicated by
several types of peculiarities that can occur in individual objects. On the
other hand, composite spectra are often not recognized as such even at
medium-high spectral resolution and typical signal-to-noise ratios, despite
multiplicity among massive stars is widespread. In particular, surveys that
produce large amounts of automatically reduced data are prone to oversight of
details that turn hazardous for the analysis with techniques that have been
developed for a set of standard assumptions applicable to a spectrum of a
single star. Much larger systematic errors than anticipated may therefore
result because of the unrecognized true nature of the investigated objects, or
much smaller sample sizes of objects for the analysis than initially planned,
if recognized. More factors to be taken care of are the multiple steps from the
choice of instrument over the details of the data reduction chain to the choice
of modelling code, input data, analysis technique and the selection of the
spectral lines to be analyzed. Only when avoiding all the possible pitfalls, a
precise and accurate characterization of the stars in terms of fundamental
parameters and chemical fingerprints can be achieved that form the basis for
further investigations regarding e.g. stellar structure and evolution or the
chemical evolution of the Galaxy. The scope of the present work is to provide
the broader community with criteria to evaluate spectroscopic investigations of
massive stars before interpreting them in a broader context. The discussion is
guided by our experiences made over a decade of studies of massive star
spectroscopy ranging from the simplest single objects to multiple systems.

Solar and Stellar Astrophysics