Situation: You served in the Army as a Public Affairs Specialist, writing news releases and the like. As part of your job you once traveled to Kabul briefly. What do you tell people about your service?
Nice guy: Tells the truth, that he worked behind the lines briefly in Afghanistan. Takes pains to point out that he never saw combat.
Average guy: Says that he served in the Army in Afghanistan. If asked exactly what his job was, tells the truth, but emphasizes that he was in danger too, carried an M4, and traveled with a patrol once. Says he thought about trying out for Special Forces (the thought fleetingly crossed his mind), but in the end decided to go to college instead.
Sociopath: Says he was a Navy Seal, and engaged in covert operations he can't talk about. Once he sees that his tough guy credentials are established, burnishes his nice guy credentials by saying he is tormented by the thought that one time there might have been collateral damage from a hand grenade he threw.
Situation: How do you react to the sight of a legless veteran in wheelchair?
Nice guy: Looks away quickly; the tear forming in his eye embarrasses him.
Average guy: Looks away, then looks back at the veteran and nods, remembering what he once read about how people in wheelchairs don't like the way they become "invisible" since people are taught that it's impolite to stare. Feels sympathy, but also thinks, better him than me.
Sociopath: Stares directly at the stumps for a few seconds with a look of rapt fascination. Then looks up at the man's face as if he is a freakish curiosity. When he is out of earshot, or perhaps not quite out of earshot, says to his buddies, "Jesus, if I was that guy I'd kill myself."
Situation: You've just put a week working for Habitat for Humanity.
Nice guy: Just hopes his work has helped a little. Doesn't really focus on his own participation, other than to worry that perhaps the quality of his work might not have been good enough. For him, the work actually is its own reward.
Average guy: Joined thinking it would be a good way to meet girls, and figures it will look good on his resume. Feels this is definitive proof that he is a good person. Manages to insert his work into every conversation. Also figures the week has bought him respite from any good deeds for a long time.
Sociopath: Sees himself as a saint. Tries to portray himself this way even to the other people at Habitat, in the process managing to annoy all of them. Walks around in a constant state of egomania about his "sainthood." Exudes "goodness" all the time. Gets quite preachy about the need to help others. Becomes angry when others don't regard him in a saintly light.