How do charging equilibria, aka charge regulation as in the case of proteins with dissociable amino acid moieties, affect the electrostatic interactions? This is a fundamental problem in biophysics, important for our understanding of interactions between the proteins and proteinaceous aggregates such as viral capsids, but also in the general colloid context, often built on the fictional foundation of fixed charges. Recent advances in the theoretical formulation and analysis of charge regulated system lead to some far reaching conclusions on electrostatic interactions in colloid milieu, that often differ fundamentally from the accepted wisdom. I will present several examples of novel behavior or new understanding of the known behavior that is specifically connected with the response of the charging equilibrium on (bio)colloidal surfaces to the local bathing solution conditions.