  In the present work we discuss certain characteristic features encoded in
some of the fundamental QCD Green's functions, whose origin can be traced back
to the nonperturbative masslessness of the ghost field, in the Landau gauge.
Specifically, the ghost loops that contribute to these Green's functions
display infrared divergences, akin to those encountered in the perturbative
treatment, in contradistinction to the gluonic loops, whose perturbative
divergences are tamed by the dynamical generation of an effective gluon mass.
In d=4, the aforementioned divergences are logarithmic, thus causing a
relatively mild impact, whereas in d=3 they are linear, giving rise to enhanced
effects. In the case of the gluon propagator, these effects do not interfere
with its finiteness, but make its first derivative diverge at the origin, and
introduce a maximum in the region of infrared momenta. The three-gluon vertex
is also affected, and the induced divergent behavior is clearly exposed in
certain special kinematic configurations, usually considered in lattice
simulations; the sign of the corresponding divergence is unambiguously
determined. The main underlying concepts are developed in the context of a
simple toy model, which demonstrates clearly the interconnected nature of the
various effects. The picture that emerges is subsequently corroborated by a
detailed nonperturbative analysis, combining lattice results with the dynamical
integral equations governing the relevant ingredients, such as the
nonperturbative ghost loop and the momentum-dependent gluon mass.
