I think most of the time the mods don't even bother to go the NDS even though they are supposed to moderate it. None of the mods with powers in the section use invisible mode except Ira. If they go to the NDS, they will be easily noticed thanks to thier unique usernames. On my time spent on NB, I can tell that seeing mods on the NDS is a rare sight indeed (The only mod that I have seen in the NDS over the recent 4 months is Klaus). Since the mods rarely go to the NDS in the first place, the mod bais claim is extremely shaky. The real bais lies not with the mods but with the members themselves who give in to thier bais and selectively report threads. Once a thread has been reported, action has to be taken and you know what happens next.
What doesn't make sense is if that troll threads are been reported, then why are other troll threads missed ? The only answer would be that the mods do not properly check all threads made in the section and only pay attention to reported threads. It makes sense cause considering how cancerous NDS is, the farther you stay away from it, the better. This gains even more importance when you are a mod.