The possibility of observing violations of temporal Bell inequalities,
originally proposed by Leggett as a mean of testing the quantum mechanical
delocalization of suitably chosen macroscopic bodies, is discussed by taking
into account the effect of the measurement process. A general criterion
quantifying this possibility is defined and shown not to be fulfilled by the
various experimental configurations proposed so far to test inequalities of
different forms.Comment: 7 pages, 1 eps figure, needs europhys.sty and euromacr.tex, enclosed
in the .tar.gz file; accepted for publication in Europhysics Letter
