Alexandar et al. (Inorg. Chem. Commun. 159 (2024) 111751) report to have grown “l-cysteine picrate” crystal (LCP) by evaporation of an aqueous solution containing equimolar ratios of l-cysteine and picric acid at 40 °C in a constant temperature bath. A critical analysis of the reported infrared spectral and X-ray powder data, reveals that the LCP crystal is, in fact, picric acid. Previously, Alexandar et al. has claimed to have grown a so-called “l-methioninium picrate” crystal (LMP) (J. Nonlinear Opt. Phys. Mater. 25 (2016) 1650052) which is also improperly characterized as it is devoid of any picrate and LMP is indeed l-methionine. Taking as examples LCP, LMP and the supposedly new crystals “l-methionine succinic acid” (Chem. Phys. Impact 6 (2023) 100203) and “(4-nitrophenyl) methionine” (Indian J. Phys. 97 (2023) 3835) which are, in fact, succinic acid and l-methionine, respectively, we highlight a combined use of infrared spectra and X-ray diffraction data for accurate characterization of known crystals.