  It has been argued recently that transverse asymmetries that are expected to
be shielded from the presence of the S-wave (Kpi) pairs originating from the
decay of a scalar K0* meson, are indeed affected by this pollution due to the
impossibility to extract cleanly the normalization for these observables. In
this short note we show how using folded distributions, which is nowadays the
preferred method to obtain the information from the 4-body decay mode B-> K*(->
Kpi) l+l-, one can easily bypass this problem and extract the clean observables
P_{1,2,3} and also P'_{4,5,6} in a way completely free from this pollution
including all lepton mass corrections. We also show that in case one insists in
using uniangular distributions to extract these observables it is possible to
reduce this pollution to just lepton mass suppressed terms. On the contrary,
the S_i observables, that are by definition normalized by the full differential
decay distribution, will indeed suffer from this pollution via their
normalization. Finally, we also present a procedure to minimize the error
associated to neglecting lepton mass corrections in the distribution defining a
massless-improved limit.
