There's a bit more going on here. Some companies give "honesty-integrity assessments" to predict whether candidates may steal from the company, sexually harass

There's a bit more going on here. Some companies give "honesty-integrity assessments" to predict whether candidates may steal from the company, sexually harass employees, etc. How do they predict whether someone would do that? They simply ask. People who steal gratuitously will often rationalize the behavior by convincing themselves that "everyone steals something." When they see the questions, they'll think that, if they mark that they would never steal anything, they'll be flagged as a liar. And then they're caught. The drug questionnaire presumably acts under similar principles. The people who mark "Hallucinogens -- once in my life" tend to be the people who pop a pill every week.