1. IMO, a mole would try to maintain a very unexceptional profile - not too visible, posts or Reports, and not too invisible. So if there are Frequent-Reporters on DU, those members probably are not moles or trolls.
2. Historically - the Reign of Terror, Hitler's SA purge, Stalin's purge of "Old Bolsheviks" - lefties turn on each other in purity and power witch hunts. If there are Frequent-Reporters on DU, ordinary DU-folk should fear Proggier-Than-Thou witch hunts. Don't be the first to stop clapping or clap too quietly, Comrade.