Oddly, I don't find this idea too offensive, especially since so many companies have large security holes via social engineering. If the applicants are this lackadaisical in keeping their own data private, why would I trust them with the company's or my customer's sensitive information?

With that said, I definitely understand why an applicant would be offended by the question. In fact, I would hope they are! I guess the second test is seeing if they understand the logic of such a question then convincing him or her that I don't conduct myself this way.

In the right hands, this is a great tool, but in the wrong hands, it is a disaster.