@Carde - did you ever play through Eastmarch or the Rift? There are a fair number of them. In Eastmarch, there is a town overrun with them that you need to kill for a quest.
Anyway, I tend to avoid them unless I really feel like killing them, but there are a fair few about in those areas.
One of the Cyrodiil skyshards is in a dungeon full of trolls.Also I gotta wonder why you're even killing them enough to warrant carrying a secondary weapon, lol. They're not used for much other than causing pain to travelers sometimes.