  We elucidate the nature of universal scaling in disordered driven models. We
in particularly explore the intriguing possibility of whether coupling with
quenched disorders can lead to continuously varying universality classes. We
examine this question in the context of the Kardar-Parisi-Zhang (KPZ) equation,
with and without a conservation law, coupled with quenched disorders of
appropriate structures. By using a renormalisation group (RG) framework, we
show when the disorder is relevant in the RG sense, the scaling exponents can
depend continuously on a dimensionless parameter that defines the disorder
variance. This result is generic and holds for quenched disorders with or
without spatially long ranged correlations, as long as the disorder remains
"relevant perturbation" on the pure system in a renormalisation group sense and
a dimensionless parameter naturally exists in its variance. We speculate on its
implications for generic driven systems with quenched disorders, and compare
and contrast with the scaling displayed in the presence of annealed disorders.
