"nerfed" is when something (a skill, grp of enemies, etc.) gets "worsened" by ANet.
Like the smite monk gvg build was waaayy to powerful so they nerfed zealots fire to only become triggered when a spell is cast. Before, people would just use warrior shouts and animal shouts or whatever and did 30+ dmg every 1/2 second...or so
but the problem with asking for farm spots that arent nerfed here in public just makes it THAT much easier for ANet to nerf it.
But trolls north of droks, hydras north of augury, ettins east of beetletun have been kinda nerfed, cave spiders in FoW, aataxes in UW......theres lots more. Just search em on these forums