  The theoretical description and data for inclusive semileptonic $B$ decays
have reached incredible precision. This motivated us to re-animate the
discussion of possible Quark-Hadron Duality violations. There seems that there
is currently no evidence of a failure of the Heavy Quark Expansion (HQE) used
to compute observables for these decays. However, we might arrive at a point
where an asymptotic behaviour of the HQE would limit a further increase of
precision. We discuss this possibility and suggest a simple model, which can be
used to study the effects of higher orders in the $1/m_b$ expansion and
possible quark-hadron duality violations. We devise observables sensitive only
to such higher-order effects to test the behaviour of the HQE. Using these
observables we obtain a first estimate of possible quark-hadron duality
violations using the measured $q^2$ moments.
