One of the dangerous encounters I occasionally had was when a dark ninja salmon suddenly appeared in front of me. I could not have seen him earlier because either he just emerged from behind a parked truck or I just made a turn onto "his" street. (So it's important for me to use front light, so that at least he could see me even if I didn't see him)
Sadly if we stop and think about it's not just our fellow cyclists who are guilty of dressing in dark colored clothing after dark. I have lost count of the number of times that I've been surpirsed by another pedestrian coming out of the shadwos.