Ebert: 
BY ROGER EBERT / July 28, 2010
The truly goofy comes shrouded in innocence. If a man is trying to be goofy, it's just an act that quickly grows old. But if he lacks the slightest notion of his peculiarity, there's the secret. The blissful ignorance of Barry Speck is beyond pitiful and ascends to a kind of nobility. He's one of those who truly doesn't have a clue.
In “Dinner for Schmucks,” a group of arrogant rich men use him as part of an elaborate joke, but the joke is on them. You can't insult a man who is always happy to be just exactly who he is. In the film, the millionaires have a dinner party every year that is a secret joke: Each guest invites another guest who is, whether he realizes it or not, in a contest to determine which guest is the biggest idiot. This is plain cruel.
