  Recently a new impulse has been given to the experimental investigation of
contextuality. In this paper we show that for a widely used definition of
contextuality there can be no decisive experiment on the existence of
contextuality. To this end, we give a clear presentation of the hidden variable
models due to Meyer, Kent and Clifton (MKC), which would supposedly nullify the
Kochen-Specker Theorem. Although we disagree with this last statement, the
models play a significant role in the discussion on the meaning of
contextuality. In fact, we introduce a specific MKC-model of which we show that
it is non-contextual and completely in agreement with quantum mechanical
predictions. We also investigate the possibility of other definitions of
non-contextuality --with an emphasis on operational definitions-- and argue
that any useful definition relies on the specification of a theoretical
framework. It is therefore concluded that no experimental test can yield any
conclusions about contextuality on a metaphysical level.
