Consider having Dirt age out, either over time, or after anything in particular is over and done.
EG: A Job helped win an election. Either 3 months, a year, something later on it won't matter that much.
OR
After this news cycle is over, or the elected person is no longer in any office, the Dirt is of less value.
I would suggest that some mooks are highly loyal, naively loyal (loyal until they learn some lesson), treacherous (looking to betray), mercenary (clear that money is how they stay loyal) etc.
I would also suggest that some have a rating for being easy or hard to take out due not to their stated ratings, but because they have people who will follow up.
You could consider the agents, or teams, to have Values, where missions that promote (or are spun to promote) the value are given higher loyalty, and where if it comes out that Other Jobs promote or hinder these values they are more or less likely to hide or share their Dirt as well.