The masses of supermassive black holes (BHs) in active galactic nuclei (AGNs) can be determined by resolving the BH sphere of influence over time using reverberation mapping (RM). The established relationship between the broad-line region (BLR) radius and AGN luminosity serves as a foundation for measuring black hole mass (MBH) across the Universe. For an increasing number of nearby AGNs, high signal-to-noise and high-cadence RM data offer new insights into BLR geometry and kinematics through dynamical modeling. Combining these independent MBH measurements with new spatially resolved host galaxy kinematics allows us to refine MBH-host galaxy scaling relations with unprecedented precision. I will discuss biases arising from varying aperture sizes, host galaxy morphologies, and AGN luminosities, and how they impact the intrinsic scatter in these scaling relations. Finally, I will explain how our findings influence the interpretation of MBH-scaling relations as tests for the co-evolution of black holes and their host galaxies.