Panels in the l.h.s. display the histograms showing the fractions of unphysical net-bulge spectra after subtraction of expD, subdivided in three bulge mass bins (low M_⋆, B for bulges with log of stellar mass lower or equal than 9.5 M_⊙, intermediate M_⋆, B for bulges with log of stellar mass between 9.5 and 10.5 and high M_⋆, B for bulges with log of stellar mass higher or equal than 10.5). From left to right: bars represent the fraction of net-bulge spectra that reached the maximum mass-weighted stellar age (blue) and metallicity (purple), display negative flux (light pink) and which estimated stellar mass is higher after disk subtraction (dark pink). Panels in the r.h.s. contain the histograms showing the fractions of unphysical net-bulge spectra that meet all the aforementioned criteria. From top to bottom: rows refer to the spectral modeling run SLZ4, SLZ5, FDZ4 and FDZ5.