In Death of a Salesman, what car does Willy say is a good car but then says is a terrible car?
Willy has sold a Chevrolet, which he first esteems as "the greatest car ever built." When his wife deflates his ego by pointing out that the gross profit he made was only $200 and when the car needs a new carburator, Willy suddenly changes his tune.
This vascillating between extremes is one symptom that something is definitely wrong with Willy's reasoning ability and mind frame. He constructs his self-worth around optimism and hyperbole instead of dealing with situations as they really are. His inability to face his problems at face value and to confront his own limitations lead him to suicide.
The absurdity of such a rash act makes him a pathetic, anti-heroic character, but onlookers of the scene (spectators or readers, as the case may be) can't help but feel sorry for Willy's dilemma - which is situational ideed, but more psychological than anything else. Whereas a more realistic person could have coped, Willy simply cops out, exchanging his life for insurance money his family will get after the "accident."
The following references are most pertinent in deciphering Willy's use of language, which is a form of denial in itself.