Are violations to temporal Bell inequalities there when somebody looks?

The possibility of observing violations of temporal Bell inequalities, originally proposed by Leggett and Garg 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