  We present experimental evidence supporting the postulation that the
secondary effects of light-assisted collisions are the main reason that the
superradiant light scattering efficiency in condensates is asymmetric with
respect to the sign of the pump-laser detuning. Contrary to the recent
experimental study, however, we observe severe and comparable heating with all
three pump-laser polarizations. We also perform two-color, double-pulse
measurements to directly study the degradation of condensate coherence and the
resulting impact on the superradiant scattering efficiency.
