One of the possible approaches to study the spectral properties of quasi particles in strongly coupled systems is to develop a theory around the limiting case invoking small polaronic charge carriers. They can be envisaged as electrons surrounded by clouds of either local charge, spin or lattice fluctuations, according to the system under investigation. Due to retardation effects between the dynamics of the respective clouds and the electrons, it is presently not established that such entities can exist in form of coherent Bloch-like states giving rise to polaronic metals or merely exist as diffusive modes, resulting in polaronic insulators. A further possibility is that the system phase segregates into regions of localized polaronic states embedded in regions where the charge carriers exist as itinerant quasi-free electrons. Such a scenario can be envisaged due to a competition between the localization energy of the polaronic charge carriers and the kinetic energy of itinerant states. Given the recent advances in material research, providing us with high Tc cuprates, the colossal magneto resistance magnates and organic polymers studied by field effect transistor devices, these questions will have to be answered in a near future.