Difference Between True Insanity and Feigned/False Insanity - ( Difference b/w mentally ill Insane person and a pretender )

Differentiate between and a true Insane person and a person who is pretending to be insane because of fear of the lawful punishment or some other motive by keeping the following things in your mind.

1. In true insane person, Onset is usually gradual or rarely sudden but almost always without any motive While in feigned insanity onset is always sudden and there is some motive
2. The predisposing or exciting cause may present in truly insane but not in a false one.
3. There are usually peculiar characteristic facial expressions in well develop cases of insanity While facial expression in false insane person is normal or easily distinguishable.
4. The truly insane individual shows signs and symptoms of insanity irrespective of his conduct being observed or not while a false insane will show signs of insanity only when he is observed and there is the total absence of symptoms when he thinks that he is alone or not being watched.
5. Sign and symptoms usually point to a particular type of insanity in truly insane. ( e.g schizophrenia, mania, Bipolar disorder etc) while a non-insane person will do whatever comes into his mind and his signs and symptoms don't indicate a particular type of insanity.
6. A truly insane person can stand violent exertion for several hours or days without exhaustion, perspiration or sleep while in a non-insane, violent exertion leads him to relaxation, exhaustion and sleep.
7. Habits of a truly insane person are invariably dirty or filthy. An insane may smear his body with stool or urine while habits are not usually dirty or filthy in non-insane Though a false show may be put to that effect. 
8. The physical manifestation of true insanity, Viz dry harsh skin, furred tongue, constipation, anorexia (loss of appetite)  and insomnia (loss of sleep ) are present in a truly insane while not in feigned insanity.
9. True insane is not worried about being repeatedly examined while a false insane person shows dislike for repeated examinations.