In John Steinbeck's Of Mice and Men the character of Carlson represents someone who has given his back to humanity and who lives in heartless contempt and sadistic carelessness towards anything that is, in fact, human or humane. He is a man who, in his quest to be "rogue", and "hard" has forgotten altogether what it feels like to be a person. As a result he spews his hateful and frigid ways onto everyone he touches. This is perhaps then what would render true the statement that he represents an American that has gone terribly awry.
Carlson is an arrogant and callous mechanic who is, contrary to the rest of the field hands, an actual skills-based needed worker. It is significant that he is a mechanic because this alludes that his conduct is similar to the way in which his machinery operates : Automated, pre-programmed, senseless, careless, predictable, artificial.
This is clearly a metaphorical way of expressing that he, as a man who has the upper hand among all the other workers has not learned from his obviously skillfulmentality to be gentle and humble, or humane, or even decent. In fact, he uses his skills to become even more mechanical, more careless, more senseless and more cruel in thought and action. In this way he would represent an America who uses its own talent for the worse. It is also a way to add on to the overall atmosphere of the story, which is set in a time where America was struggling as much as are George and Lennie in the story.
It is Carlson who entices Candy to kill his dog, who cracked a sad joke at Slim and George after George shoots Lennie, and he also is the one who belittles and emasculates Curley even in front of the other field hands (which is, by far, the only thing the reader may appreciate from his character) and insults Curley saying
"You God damn punk," he said. You tried to throw a scare into Slim, an’ you couldn’t make it stick. Slim throwed a scare inta you. You’re yella as a frog belly. I don’t care if you’re the best welter in the country. You come for me, an’ I’ll kick your God damn head off."
Therefore, judging from the way that he talks to others, what he feels about others, and how he acts towards his neighbors we can certainly conclude that Carlson is the worst representative of the All American hero that we hope to see nurtured in the hearts of all of the hard working men who have to suffer to earn their bread. If anything Carlson would be a social embarrassment, indeed.