In order to see if a police official is wearing a name tag you have to be close to him or her which means that you are in a one to one situation with the official. If he or she is not wearing a name tag you cannot just ignore them but you have the right to ask the official to identify him or herself by showing their appointment card, which must be carried by each and every police official, even the personnel appointed under the Public Service Act in the South African Police Service carries distinct appointment cards which are issued to them. If the official refuse to identify him or herself by showing their appointment card you can demand that you wish to speak or be approached by the official's supervisor or commander.
Furthermore you must remember that if you feel unsafe for instance when followed and instructed by an apparent police official whilst driving, you can drive to the nearest police station in order to make sure that it is a bona fide police official that instructed you to pull over.
Remember that police officials attached to the detectives in the South African Police Service are working in normal private clothes and do not wear name tags. If you are approached by an official claiming to be a detective you must always ask him or her to identify themselves by presenting his or her appointment card.