  In spite of many attempts, no local realistic model seems to be able to
reproduce EPR-Bell type correlations, unless non ideal detection is allowed.
The low efficiency of detectors in all experiments with photons makes the use
of the fair sampling assumption unavoidable. However, since this very
assumption is false in all existing local realistic models based on inefficient
detection, we thus question its validity. We show that it is no more reasonable
to assume fair sampling than it is impossible to test, and we actually propose
an experimental test which would provides clear cut results in case of unfair
sampling.
