A system for monitoring displayed content, such as advertisements, has at least one sensor that is used to monitor an electronic display and provide information about the operation of the display, such as the content being displayed or whether one or more components of the display are operating correctly. The sensor is selected, positioned, and/or otherwise configured to limit the its ability to collect information in the environment surrounding the display so as to reduce concerns about the use of the sensor in a private or secure environment. The system may be used to confirm that the hardware of the display system is operating correctly and displaying the proper content at the proper times.