The dense double ionization spectra of all the twelve fluoro-substituted benzene molecules are investigated in great detail by Green's function ADC2 calculations and a two-hole density mapping. Double ionization is shown to provide an extremely sensitive tool of electronic structure analysis. The calculations evidence and measure quantitatively how the charge distribution is dictated by the complex interplay between the resilience of the aromatic ring electronic structure and the disruptive effect of the electronegative halogen substituents. Successive substitutions are found not to have any synergic effect, but affect the spectra in very identifiable ways. The Auger spectra of the fluorobenzenes are interpreted in the light of the charge distribution results, using the foreign-imaging model. The double charge transfer spectra are also analyzed and discussed.