  We discuss the preliminary results of an extensive effort to address the
fundamental, and yet un-answered, question that can be trivialized as: ``are
there more blue or red blazars?''. This problematic is tightly connected with
the much debated issue of the unified picture(s) of radio-loud AGNs, which in
turn revolves around the existence, and the properties of relativistic jets. We
address this question by comparing -- simultaneously -- the properties of the
collection of heterogeneously selected samples that are available now, with the
predictions of a set of plausible unifications scenarios. We show that it is
already possible to make significant progress even by using only the present
samples. The important role of selection effects is discussed. For instance we
show that the multiple flux selections typical of available surveys could
induce some of the correlations found in color-color diagrams. These latter
results should apply to any study of flux limited samples.
