With the availability of easy-to-use commercial instrumentation for infrared (IR) and Raman spectroscopy, the number of users is growing very fast. Even in labs in which no personnel with experience in spectroscopy is around, spectra can be recorded and analyzed. However, for an inexperienced person it is virtually impossible to check whether a spectrum is plausible. In this Note, it is demonstrated that even comparing an experimental spectrum with data from a database may lead to significant errors. The vibrational spectrum of dimethyl sulfoxide (DMSO) is presented as an example.