  We have analyzed the Gaussian decomposition of the Leiden/Dwingeloo Survey
(LDS) of galactic neutral hydrogen for the presence of Gaussians probably not
directly related to galactic HI emission. It is demonstrated that at least
three classes of such components can be distinguished. The narrowest Gaussians
mostly represent stronger random noise peaks in profiles and some still
uncorrected radio-interferences. Many of slightly wider weak Gaussians are
caused by increased uncertainties near the profile edges and with the still
increasing width the baseline problems become dominating among weak components.
Statistical criteria are given for separation of the parameter space regions,
most likely populated with the problematic components from those where the
Gaussians are with higher probability describing the actual Milky Way HI
emission. The same analysis is applied to the Leiden/Argentina/Bonn survey
(LAB). It is demonstrated that the selection criteria for dividing the
parameter space are to a great extent independent of the particular survey in
use. The presence of the baseline problems in the LDS is indicated by the
peculiarities of the distribution of the widest Gaussians in the sky. A similar
plot for the northern part of the LAB demonstrates considerably lower numbers
of spurious components, but there are still problems with the southern part of
the LAB. The strange characteristics of the observational noise in the southern
part of the LAB are pointed out.
