Progress in near-field optical spectroscopy research on metal narroparticles demands a better understanding of the role of particle-particle and tip-sample interactions. In this perspective, we investigate theoretically, at a very moderate level of sophistication, the optical behavior of simple silver nanoparticle aggregates, in terms of a formalism involving a multipolar expansion of the fields involved, along with a simplified model for the optical behavior of nanostructures previously developed. In particular, the tip-sample interaction is taken into account roughly, treating the tip as an additional, single particle, characterized by proper dielectric behavior.