  In this talk we review the limitations of including meson loops as
perturbative corrections in a solvable quark model. We first discuss
meson-meson scattering within a formalism which treats confined quark pairs and
mesons on an equal footing. The interaction between the mesons proceeds through
$s$-channel meson-exchange diagrams. Next, we develop a perturbative expansion
of the model, and show that the resonance poles found in such a treatment, even
by accounting for contributions up to fourth order, do not coincide with those
obtained with the full model. We conclude that the resonance predictions based
on perturbative approximations in quark models are not reliable, especially in
those cases where the coupling to the scattering channels is large.
