Apparatus and method is provided for using low cost, passive RF sensor technology such as RFID tags, to determine whether containers or other objects are in a right-side-up orientation. A useful embodiment of the invention is directed to sensor apparatus for use in detecting an improper orientation of a conventional box or container with respect to a substantially horizontal surface. The apparatus includes a structure having two sides formed of plastic in spaced apart relationship, to define an enclosed space within the structure. Selected shielding material attached to the structure shields a specified region of the enclosed space against RF signals, the shielded region being located in the lowest portion of the enclosed space when the structure is in a reference orientation with respect to the horizontal surface. An RFID tag embedded in a disk is positioned in the enclosed space, the disk being sized to move freely within the space. A guide element guides the disk in moving between the shielded region and an unshielded region, when the structure is correspondingly moved between its reference orientation and an improper orientation corresponding to an improper orientation of the container. This allows a signal to be received from the RFID tag when it becomes unshielded, to indicate improper container orientation.