I noticed this on another Forum posted by a user called Jethrine and thought it might help some of you , did do a quick search and checked the topics brought up in the similar threads ......
I was grinding my scavenging skill in the inevitable city by dotting the mobs that fight near the big arena area. As long as you get some damage in you get to loot/scavenge. While doing this I noticed I was often getting full xp for the mobs even though they never broke off from fighting each other. All you have to do is dot both mobs whenever they pop and start fighting and you will get full xp (most of the time) from both mobs even though only the victor will eventually charge you mostly dead. I was able to keep 4-8 mobs dotted and was raking in the xp and vendor junk/scavenged items.
This will work anyplace where mobs are fighting each other. At lower levels, you may need to damage more, but it is confirmed as working.