  We consider an $L^2$-Wasserstein type distance $\rho$ on the configuration
space $\Gamma_X$ over a Riemannian manifold $X$, and we prove that
$\rho$-Lipschitz functions are contained in a Dirichlet space associated with a
measure on $\Gamma_X$ satisfying some general assumptions. These assumptions
are in particular fulfilled by a large class of tempered grandcanonical Gibbs
measures with respect to a superstable lower regular pair potential. As an
application we prove a criterion in terms of $\rho$ for a set to be
exceptional. This result immediately implies, for instance, a quasi-sure
version of the spatial ergodic theorem. We also show that $\rho$ is optimal in
the sense that it is the intrinsic metric of our Dirichlet form.
