  Foreground contamination is the fundamental hindrance to the cosmic microwave
background (CMB) signals and its separation from it represents a fundamental
question in Cosmology. One of the most popular algorithm used to disentangle
foregrounds from the CMB signals is the "internal linear combination" method
(ILC). In its original version, this technique is applied directly to the
observed maps. In recent literature, however, it is suggested that in the
harmonic (Fourier) domain it is possible to obtain better results since a
separation can be attempted where the various Fourier frequencies are given
different weights. This is seen as a useful characteristic in the case of noisy
data. Here, we argue that the benefits of using such an approach are
overestimated. Better results can be obtained if a classic procedure is adopted
where data are filtered before the separation is carried out.
