As far as I know, they may have special powers, but unless there is an event or any other reason to act, they tend not to mess with players experience

. I would also believe from previous official communications that CSRs must follow a certain procedure and obey a given set of rules given by Nevrax...
I am guilty as well (specially at the game early stages) of thinking that GMs had acted in some way.("the mob came from nowhere, it was a GM!"... "BAh the GM spawned the kinchers on us, they never pop here")... most of the times (if not all) it was purely unfounded... afaik, there are no "conspiracy theories" and GMs have other things to do rather than "have fun" at the expenses of players

(aaaaalthough, not 100% sure)
Except exceptional reasons (AI bug, server reboot, etc.) which are less and less frequent, lack of mob spawn is usually caused by a stalled mob of the group that has not been killed, although there are cases where it is just the effect of the seasons, etc. dynamic world. This can be seen as a Good Thing (TM) unless, of course, the group was on a HuntSession (TM)
Regards,