  To investigate the possibility of a ghost-antighost condensate the coupled
Dyson--Schwinger equations for the gluon and ghost propagators in Yang--Mills
theories are derived in general covariant gauges, including ghost-antighost
symmetric gauges. The infrared behaviour of these two-point functions is
studied in a bare-vertex truncation scheme which has proven to be successful in
Landau gauge. In all linear covariant gauges the same infrared behaviour as in
Landau gauge is found: The gluon propagator is infrared suppressed whereas the
ghost propagator is infrared enhanced. This infrared singular behaviour
provides indication against a ghost-antighost condensate. In the
ghost-antighost symmetric gauges we find that the infrared behaviour of the
gluon and ghost propagators cannot be determined when replacing all dressed
vertices by bare ones. The question of a BRST invariant dimension two
condensate remains to be further studied.
