I agree. There should be a faction for Clan Torn Ear (that's the name of the clan that defeated the Splitpaw gnolls and took their home). Faction changes when you kill one would probably be something like down: Clan Torn Ear Up:Splitpaw Clan, Sabertooths of Blackburrow, Karana Residents, and Guards of Qeynos. Clan Torn Ear Splitpaw clan for obvious reasons, Sabertooths becuase their allies of the Splitpaw gnolls, and Karana Residents and Guards of Qeynos because just hate gnolls.
Just wondering, but why doesn't killing gnolls in Splitpaw and Southern Karana have any effect on faction? I know the faction changed when the Splitpaws were run out (killing the rarer Splitpaws in Blackburrow has the same effect that killing Splitpaws in Paw ans SK used to) but these should have some kind of faction. At least raise Guards of Qeynos and Karana Residents, who hate these gnolls as much as the old ones. Should also create a new faction for these that lowers when you kill them.
As it is, they're RTA to everyone. No faction hits, positive or negative, when killing them.
Although I know that this post will be rated as awful... I once had a dream that I was playing EverQuest and wound up in front of a group of Splitpaw Gnolls; I conned them and they were all indifferent. Fun dream.