I have had a few matches finished mainly because of opposition suddenly dissapearing from ASB. I usually do not trust people until they have stuck around for some time, so I know they won't dissapear. I usually have 1-1's or 2-2s for that reason, but at the moment I am in a 4-4, a 3-3 and a 1-1.
I always finish reffings because I feel I have a duty to ref. Anyway I like to feel somewhat important.