  It is possible to improve the chiral behaviour and the approach to the
continuum limit of correlation functions in lattice QCD with standard and
twisted Wilson fermions by taking arithmetic averages of correlators computed
in theories regularized with Wilson terms of opposite sign. To avoid the
problem of the spurious zero-modes of the Wilson--Dirac operator, twisted-mass
lattice QCD should be used for the actual computation of the correlators taking
part in the averages. A particularly useful choice for the twisting angle is
$\pm\pi/2$ where many physical quantities (e.g. masses and zero-momentum matrix
elements) are automatically improved with no need of averaging.
