Black dots: percentage of catastrophic photometric redshift failures in the 33 T0006 candidate clusters in the VVDS spectroscopic area as a function of S/N. The point at S/N = 3.5 was obtained by combining the S/N = 3 and S/N = 4 data. Red dot: percentage of catastrophic photometric redshift failures in the S/N = 2 T0006 candidate clusters in the VVDS spectroscopic area also detected by A10. The horizontal line shows the mean percentage of catastrophic photometric redshift failures for the whole photometric redshift sample (not only in clusters) in the VVDS area.