Advantages: You do not get treated differently because of what you are there to do, you get a real feel for what you are observing as people do not know what they are being observed and so donot act differently than they normally would.
Disadvantages: It can be seen as morally wrong and an invasion of privacy as the people donot know they are being observed
Disadvantages: It can be seen as morally wrong and an invasion of privacy as the people donot know they are being observed
