Prankvertising

Few weeks ago LG decided to advertise their Ultra HD TV by installing hidden cameras during a job interview reaching a wide audiences virally.
Recently, producers of Carrie, a new horror movie, have also attempted to prank coffee drinkers in order to promote their motion picture.
The production is unbelievable however, what are the limits of using random consumers in a promotional material. In the end of the day, both a job interview & having a coffee tend to be occasions in which people are either extremely stressed out or try to relax.
Is prankvertising an acceptable form of advertising or is it pushing the limits a little bit too far?