Ratio of velocity dispersion measurements between “full” and “clean” XSL (red), MILES (blue), and Indo-US (green) libraries. The markers denote the ratio of the velocity dispersion measurements for individual galaxies in the MUSE sample and the horizontal dashed lines mark the sample average for each library. While the effect of cleaning the libraries is most prominent for XSL, it is evident that this is a crucial process in achieving high accuracy.