  The cosmological potential of large-scale structure observations for
cosmology have been extensively discussed in the litterature. In particular, it
has recently been shown how Sunyaev-Zel'dovich (SZ) cluster surveys can be used
to constrain dark energy parameters. In this paper, we study whether selection
and systematics effects will limit future wide-field SZ surveys from achieving
their cosmological potential. For this purpose, we use a sky simulation and an
SZ-cluster detection software presented in Pires et al. (2005), using the
future Olimpo, APEX and Planck surveys as a concrete examples. We show that the
SZ-cluster selection function and contamination of SZ-cluster catalogues are
more complex than is usually assumed. In particular, the simulated
field-to-field detected cluster counts is a factor 3 larger than the expected
Poisson fluctuations. We also study the impact of missing redshift information
and of the uncertainty of the scaling relations for low mass clusters. We
quantify, through hypothesis tests, how near-future SZ experiments can be used
to discriminate between different structure formation models. Using a maximum
likelihood approach, we then study the impact of these systematics on the joint
measurement of cosmological models and of cluster scaling relations.
