  We study the redshift space correlation function of galaxy clusters for
observational samples constructed in different surveys. We explore correlation
amplitudes, pairwise velocity distributions and bias factors. Systematics in
cluster identification procedures are the main source of biased estimates of
the correlation amplitude and inferred velocity dispersions. By comparing our
results with those of numerical simulations we explore the strong influence on
the clustering distortion pattern in redshift space from effects associated
with the cluster identification procedure from two dimensional surveys as is
the case of Abell and APM clusters. The identification of clusters in X-ray
surveys improves this situation, although there are still systematic effects
which are probably due to identification of optical sources in the
determination of cluster redshifts. These systematics are particularly strong
for the most luminous X-ray selected clusters in the Extended Bright Cluster
Survey, which exhibits very large anisotropies, comparable to those present in
the Abell catalogue. Our results demonstrate that forthcoming large redshift
surveys will be extremely important for the construction of new samples of
groups and clusters as well as improving the determination of optical and X-ray
selected cluster distances, essential for reliable analyses of the large scale
structure.
