ROFL. This is not only hysterical but also incredibly insightful.
tl/dr: Some people who have language disorders are unable to understand the meaning of words. Instead, they rely on facial expression and tone. In other words, they compensate their linguistic incompetency with an infallible precision and sensitivity to "tone" and feeling. People who have a particular language disorder called aphasia can't be lied to because they can't grasp the words being used to deceive. A psychologist describes the patients in an psych ward listing to Ronald Reagan's presidential speech and laughing hysterically. Why? Because, even though most in the ward couldn't understand the words, they could tell by their other perceptions that he was lying. A patient who had tonal agnosia (a former English teacher) said of the president's speech: "He is not cogent. He does not speak good prose. His word-use is improper. Either he is brain-damaged, or he has something to conceal."
Here then was the paradox of the President's speech. We normals - aided, doubtless, by our wish to be fooled, were indeed well and truly fooled. ('Populus vult decipi, ergo decipiatur'). And so cunningly was deceptive word-use combined with deceptive tone, that only the brain-damaged remained intact, undeceived.