  We analyze the alignment of the low multipoles (quadrupole and octupole) of
various maps of the WMAP 5yr release: the CMB maps obtained with ILC and MCMC
methods, the CMB map in the V band after foreground reduction, and, for
comparison, the (not cleaned) V band map. We study how much this alignment is
polluted by residuals on the Galactic region. Among the considered maps, the
WMAP-ILC turns out to be the most clean map from the point of view of the
proposed test. This result has been found studying the redistribution (due to
the masking process) of each bin of the probability distribution functions of
the alignment estimators. By construction, our method, feasible through Monte
Carlo simulations, works for any possible mask adopted in the analysis of data
from current and forthcoming CMB anisotropy experiments and it can only exclude
that the considered map is clean.
