When people in the 9/11 Truth movement accuse each other of being government agents, an all too common type of “evidence” is guilt by association. A has some connection to B, who in turn has some connection to C, who in turn has some connection to the CIA or some other spy agency, or perhaps a connection to an elite fraternity such as the Skull and Bones. Therefore, A must be an agent, or at least we should all worry that A might be an agent.
Similar “connections” to the Communist Party were a staple of the McCarthy-era witchhunts back in the 1950′s.
The problem with this kind of “reasoning” is that there are also huge numbers of innocent non-agents who, knowingly or unknowingly, are likely to have indirect connections either to spy agencies or to elite fraternities.