The paper reports significant variations in the Raman spectra of single-layer graphene samples obtained by micromechanical cleavage, indicating the presence of excess charges even without intentional doping. The G peak shift and width, as well as the position and relative intensity of the second-order 2D peak, are used to estimate doping concentrations up to \(\sim 10^{13} \, \text{cm}^{-2}\). Asymmetric G peaks suggest charge inhomogeneity on the scale of less than 1 \(\mu\text{m}\). The study analyzed over 40 monolayer graphene samples with different areas, showing that Raman spectroscopy can fingerprint differences between nominally identical samples. The findings reconcile the variation in electrical properties of nominally identical samples and highlight the importance of checking uniformity. The analysis also reveals that "pristine" samples exhibit significant doping variation, with some showing high doping levels. The 2D peak is sensitive to doping, with hole doping causing an upshift and electron doping causing a downshift. The study concludes that Raman spectroscopy is a powerful tool for monitoring the quality of graphene.The paper reports significant variations in the Raman spectra of single-layer graphene samples obtained by micromechanical cleavage, indicating the presence of excess charges even without intentional doping. The G peak shift and width, as well as the position and relative intensity of the second-order 2D peak, are used to estimate doping concentrations up to \(\sim 10^{13} \, \text{cm}^{-2}\). Asymmetric G peaks suggest charge inhomogeneity on the scale of less than 1 \(\mu\text{m}\). The study analyzed over 40 monolayer graphene samples with different areas, showing that Raman spectroscopy can fingerprint differences between nominally identical samples. The findings reconcile the variation in electrical properties of nominally identical samples and highlight the importance of checking uniformity. The analysis also reveals that "pristine" samples exhibit significant doping variation, with some showing high doping levels. The 2D peak is sensitive to doping, with hole doping causing an upshift and electron doping causing a downshift. The study concludes that Raman spectroscopy is a powerful tool for monitoring the quality of graphene.