There are roughly two types of the mobs - easy ones and pain-in-the-ass ones. Easy ones are social, tend to attack together, and have a bit over 6k hp. Hard ones are, um, hard. They are separate, have over 40k hp and have some nasty skills. Easy ones are named Obscenity and Filt-Changed, all others take long to kill and should be avoided (Filtiopaths and Shurs).
The important thing is, that easy and hard mobs do not share the social aggro. Small groups usually consist of 1 hard (usually Shur, Filtiopaths tend to wander around alone) and a few easy mobs. When approached carefully, easy mobs can be pulled without triggering the hard one. But that is quite risky and unnecessary, because in some spots easy mobs stand in big groups, with only patrolling Filtiopaths being dangerous.
Here is the map where these easy-to-kill groups are, it is possible to farm them, while avoiding hard fights. Mobs drop signets, ritual fragments and count for Filthy Human kill achievement.
