If you're team has an RM (or a recent convert) on it, I'll root for that team and, especially, that individual...
That makes me a USU fan because they always have an impressive load of RM's.
More importantly, I make it expressly clear to the other team's fan that might be trying to talk smack that that is my criteria. I don't care about your fan base, I don't care about your school, I don't care about your wins & losses--those aren't as important to me anymore as what people do with their lives. Some of you will HATE that comment but fortunately I'm old enough to not care about that either...