  By comparing successful quark-gluon vertex interaction models with the
corresponding interaction extracted from lattice-QCD data on the quark's
propagator, we identify common qualitative features which could be important to
tune future interaction models beyond the rainbow ladder approximation.
Clearly, a quantitative comparison is conceptually not simple, but
qualitatively the results suggest that a realistic interaction should be
relatively broad with a strong support at about $0.4-0.6$~GeV and
infrared-finite.
