  A simple local hidden-variables model is exhibited which reproduces the
results of all performed tests of Bell\'{}s inequalities involving optical
photon pairs. For the old atomic-cascade experiments, like Aspect\'{}s, the
model agrees with quantum mechanics even for ideal set-ups. For more recent
experiments, using parametric down-converted photons, the agreement occurs only
for actual experiments, involving low efficiency detectors. Arguments are given
against the fair sampling assumption, currently combined with the results of
the experiments in order to claim a contradiction with local realism. New tests
are proposed which are able to discriminate between quantum mechanics and a
restricted, but appealing, family of local hidden-variables models. Such tests
require detectors with efficiencies just above 20%.
