If we catch someone consistently voting low for one team, and high for another, which used to happen a lot when the teams were Romance and Angst, we may null every one of their votes. Or, if someone votes only intermittently and always votes extremely low - we assume that they have some kind of agenda, and may null those. Sometimes, it's clear a person voted with a bias - 99% of the voters judged one way, and this one voter skewed the opposite, it's clear they are not voting fairly, and we consider that, too.
That sort of thing. Because of the sheer number of votes, it is really impossible for one voter to skew the system. But we are constantly vigilant, anyways. The Champions (and mods) work hard for their Team Votes, so we think it's only fair that we keep an eye out.