Pre employment personality tests, long a staple across corporate America, are starting to become popular among the middle-sized and small US businesses as well. It's a small wonder -- they help to select the most effective employees from what is, with the current economic conditions, a vast pool of candidates.
Most such tests have questions that are easy to manipulate. Realistically, when the question is "I have a good work ethic", why would you ever say anything other than "Strongly Agree"? It seems like such an obvious thing to say that you might wonder why they ask in the first place. The real answer is that they measure how much the applicant actually cares about getting the job -- if they don't really want it, they won't take the time to figure out and give the correct answers. Just a few of these "obvious" questions, and the applicant pool is cut in half. Quick win for the business.
More complex are the questions like this one: "Other people see me as hardworking." These questions serve a dual purpose: first, to measure honesty, and second, to measure social intelligence. An applicant that answers "Strongly Agree" to the statement "I am hardworking," but answers "Maybe" to the statement "Other people see me as hardworking" is admitting that either they lied about the first answer or they simply honestly believe that they are misunderstood -- which indicates poor social intelligence.
Also intended as a measure of honesty are the questions that seem like repeats of previous questions. If you answer "Strongly Agree" to the statement "I am punctual," but then later answer "Disagree" to "I have never been reprimanded for tardiness," your actual level of punctuality isn't in question at all -- but you can be certain that your employer won't see you as an honest person.
As an employer, however, you should be careful of making judgments like that based on the answers of pre employment screening tests. When reviewing the answers, it should always be foremost in your head that human behavior is contextual. What that means is that people act differently in different contexts, and there are a lot of factors out there that can influence the answers real people give to these test questions.