A few years back I was tangentially involved in a very clever study involving the executive ethics that was designed to address this concern.
Some of the questions were routine business questions, others were general questions about the material they read, and, the meat of the questions were ones on the moral consequences of executive decisions. It was expected that executives would answer all the questions correctly. Instead, the study scored based on how long it took them to answer the moral questions as opposed to the general questions. These scores were then compared against respondents from a control group of non-executives.
EDIT:
Gosh! I hope I'm representing her study accurately... "Business Experience and Moral Awareness: When Less May be More", Jennifer Jordan (2005)
Some of the questions were routine business questions, others were general questions about the material they read, and, the meat of the questions were ones on the moral consequences of executive decisions. It was expected that executives would answer all the questions correctly. Instead, the study scored based on how long it took them to answer the moral questions as opposed to the general questions. These scores were then compared against respondents from a control group of non-executives.
EDIT: Gosh! I hope I'm representing her study accurately... "Business Experience and Moral Awareness: When Less May be More", Jennifer Jordan (2005)