Nielsen Gullibility Ratings

Rather than measure whether a political candidate is lying poorly, which is simply a method of getting more psychopaths (who lie convincingly) into office, how about getting a measurement of how much people actually believe the words coming out of a politician's mouth ?

In a manner not completely dissimilar to the 'Nielsen Ratings' of TV fame, set up polygraphical devices in the homes of a large amount of randomly picked individuals who will be watching the speech/debate/used-car-commercial.

The device measures how much the people actually believe their, potential or actual, leaders' statements at any given time; the results are displayed realtime superimposed onto the broadcast.

Of course the potential downside is that people who know better but still choose to go along with their candidate's bullshit also register disbelief, thus the number of the politician's supporters who refuse or beg off their "Nielsen Duty" are factored into the results as well.