There is a manual procedure to do that, in one of Asimov's Foundation book. Some Empire officer, described pretty much as a Sun King aristocrat, spends some day

There is a manual procedure to do that, in one of Asimov's Foundation book. Some Empire officer, described pretty much as a Sun King aristocrat, spends some days in Terminus and the secret service records every word that comes out of his mouth. Removing all platitudes, obvious lies and adulation the result is a blank page :) I loved that.