  We continue a previous work in which {\em a priori} estimates were derived on
subgrid stress and subgrid flux for filtering schemes used in the turbulence
modelling method of Large-Eddy Simulation (LES). The estimates were derived
there as rigorous consequences of the exact subgrid stress formulae from
Navier-Stokes equations under the conditions assumed for velocity fields in the
Parisi-Frisch ``multifractal model.'' It was also shown that these assumptions
are realistic in an extended inertial range. Therefore the estimates must be
obeyed by any faithful subgrid model and we use them here to evaluate some
popular models of the subgrid stress (Smagorinsky, Bardina, etc.) We also
examine the effects of the choice of filter function on the magnitudes of
subgrid stress and transfer. Under mild assumptions on the filter these
quantities are determined by local-in-wavenumber, inertial-range interactions
and can be modelled in a universal way. However, one common choice of
filter---the sharp cutoff filter in Fourier space ---does not satisfy the
modest required conditions and we show that the associated flux, including
``backscatter'' effects, may be spuriously dominated by nonlocal-in-wavenumber,
convective processes of a non-universal type.
