Since the questionnaire relies on client self-report, all responses should be verified by the clinician, and a definitive diagnosis is made on clinical grounds taking into account how well the client understood the questionnaire, as well as other relevant information from the client.
The labels Special, Crafty, Wild and Mean can be used to give feedback to respondents -- much less threatening than the scientific labels Machiavellianism, Narcissism, Psychopathy and Sadism respectively.
The term dark personalities refers to a set of socially aversive traits in the subclinical range. Not extreme enough to invite clinical or forensic attention, they can get along (even flourish) in everyday work settings, scholastic settings, and the broader community.
Narcissists are grandiose self-promoters who continually crave attention. You have undoubtedly been annoyed by these tiresome braggarts. Machiavellians are master manipulators. At least one of them has cheated you out of something valuable—a fact that you may not have realized until it was too late. An everyday sadist has tried to hurt you, verbally or physically, for pure enjoyment. Workplace bullies are classic examples—as are trolls on the Internet. Arguably the most malevolent, a psychopath may have caused you serious harm in an impulsive fit of callous thrill-seeking.
Unless one uses social malevolence as a criterion, Dark Tetrad traits should not be considered inherently psychopathological.