I've been updating my lecture notes on 'PR as publicity'.
Traditionally, the academic world has not shown an interest in this field. Yet Jacquie L'Etang, the academics' academic, wrote this in her new textbook in a discussion of celebrity PR:
'Much of the PR role in celebrity circles is focused on promotion, publicity and media relations, and public relations has received some of its bad press from this association’. Yet ‘according to public relations scholarly conventions, publicity is a small part of public relations’.
Publicity is the most visible part of PR, and so it's open to criticism and discussion. There's criticism when PR stunts backfire, as happened to a mobile phone company in Latvia. There's much discussion when individuals create hoaxes as an attention-seeking ruse.
I'm not sure the public is any more or less gullible than in the past, but the speed with which rumours can circulate from blog to newsroom and on to social media sites makes it easier to set the hare running (and makes fact-checking online a difficult exercise).
I can defend PR-as-entertainment (in the style of 'Freddie Starr Ate My Hamster'). But a discussion of PR as publicity has to lead into a discussion of ethical principles. Good causes have to adhere to first principles, however much they may be tempted to use shock and exaggeration to further their aims.
PR Studies 
If we ride our time machine back to 1983, we find Grunig and Hunt’s “4 Models of Public Relations Practice.” The theory is positioned as an evolution of sorts, with “Press Agentry” (aka, the “publicity model”) as the lowest form of PR life — you know — the fish that crawls from the pond.
Publicity is not considered among the higher forms of practice, and the cases to which you link illustrate why. But I remind my students that certain PR challenges — fundraisers for worthwhile charities or promotions for new movies — often require that we “create the news.” I’ve done it many times, including one successful Guinness World Record stunt that earned national coverage. The story also brought thousands of new customers to my client’s venue.
But you are correct. Publicists too often contribute to PR’s bad reputation by failing to consider the ethics of their deeds. For too many, the end justifies the means — at least until they are caught in a lie.
I have a problem with the phrase “Publicity is not considered among the higher forms of practice” which stems from its lack of clarity. What is meant by ‘publicity’? In what sense is is not considered among the higher forms of practice? What practice? By whom?
If we are talking about the PR or corporate communications industry, then I would humbly point out that publicity (of some sort, on some level) is the aim of everything that we do – from writing a news release, through the creation of the annual report, via investor relations, to lobbying of public figures.
‘Stunt’ PR is one way of generating publicity (and by ‘stunt’ PR, I include use of celebrity and also the publicising of celebrities themselves through use of their own celebrity)and I agree with everything that’s written here – it needs to be subject to the ethics of our trade (amongst which are don’t lie, don’t misrepresent, don’t insult, belittle or demean).
But publicity is not ‘among the forms of practice’. Publicity IS the practice.
If you’re looking for an example of publicity gone bad, look no further than the 2007 Boston Bomb Scare. Long story short, a TV show called Aqua Teen Hunger Force sent Boston into a state of panic over a possible terrorist threat when in reality the entire event was some publicity gaining stunt. This is a case where bad PR ultimately led to changed legislation.
Here’s a link to going into more detail: http://en.wikipedia.org/wiki/2007_Boston_bomb_scare#Public_reaction