Some remarks on Bell's Inequality tests
  We emphasize the difficulties of an experiment that can definitely discriminate between local realistic hidden variables theories and quantum mechanics using the Bell CHSH inequalities and a real measurement apparatus. In particular we analyze some examples in which the noise in real instruments can alter the experimental results, and the nontrivial problem to find a real "fair sample" of particles to test the inequalities. 
A. Feoli and S. Rampone