  In this short note, we come back to the recent proposal put forward by
Kharzeev and Levin [PRL 114 (2015) 24, 242001], in which they
phenomenologically couple the non-perturbative Veneziano ghost to the
perturbative gluon, leading to a modified gluon propagator (the "glost") of the
Gribov type, with complex poles. As such, a possible link was made between the
QCD topological \theta-vacuum (Veneziano ghost) and color confinement (no
physically observable gluons). We discuss some subtleties concerning gauge
(BRST) invariance of this proposal, related to the choice of Feynman gauge. We
furthermore provide an example in the Landau gauge of a similar
phenomenological vertex that also describes the necessary Veneziano ghost but
does not affect the Landau gauge gluon propagator.
