If Michael Jackson's recent experience is anything to go by, those tempted by the attractions of participating in a fly-on-the-wall documentary may like to think again.
What starts off as a beautiful relationship between subject and film maker can leave reputations in tatters and, in Jackson's case, kick up a media storm.
And it's not only celebrities who can be left wondering where it all went wrong. For example, the BBC's Secret Life of the Office programme, featuring Holiday Autos' call centre, made great viewing for couch potatoes, but given the airing of some employees' complaints may not have been so warmly received by owner Clive Jacobs.
However, as the TV schedules become increasingly packed with fly-on-the-wall documentaries, ranging from ITV1's Facelift Diaries to the BBC's The Food Police and its recent expose of Carole Caplin and Peter Foster in The Conman, His Lover and The Prime Minister's Wife, the question is whether the subjects of these programmes can be trained to survive the experience.
In the face of what may be days, or even months, of ongoing intrusion by cameras, lights and microphones, is it possible for stars of the show to walk away as winners rather than losers?
'I think that you can, with the right advice, prepare somebody very effectively for a fly-on the-wall,' says independent communications coach Richard Phillips. 'But you have to take great care and it's important to understand from the very beginning what it is you want to get out of it.'
In other words, if you are like Elton John, and not worried by every element of your life coming under scrutiny, then giving your partner unrivalled access to film Tantrums and Tiaras is just fine. Otherwise, don't do it.
In his time, Phillips has worked with both senior business people and celebrities involved in fly-on-the-walls and he highlights that as with all interviews, success lies in being honest, but not necessarily completely open.
'For example, one female client who was involved in a fly-on-the-wall, was going to ask the crew not to film if her famous friend visited,' he says. 'My advice was to tell the friend to stay away while the crew was there.'
Likewise, when Louis Theroux interviewed Ann Widdecombe, the Tory MP put her foot down, forbidding any filming of her bedroom or interviews with her mother. She may have failed on the last point, but, the ensuing dispute not only produced highly entertaining TV, it also showed Widdecombe in a good light, prepared to put up a fight on behalf of her elderly parent.
However, some question the wisdom of taking part in such programmes at all. 'Fly-on-the-wall documentaries take no prisoners, so my advice is always "don't do it",' says MacLaurin Media chairman Brian MacLaurin.
MacLaurin highlights the conflicting agendas of the programme maker and the subject and adds: 'A one-hour programme has to be interesting and the interesting bits are always where the conflict is, not the bits where people look good.'
Over the years, MacLaurin has had a couple of clients who have either ignored or not asked for this advice, and done so at their peril. Last December, MacLaurin and his colleague Ian Monk were tasked with advising Carole Caplin and Peter Foster around their involvement in the so-called Cheriegate affair. At the height of this scandal, when Cherie Blair was accused of dealing with known fraudster Foster to purchase two flats in Bristol, Caplin and Foster allowed programme maker and Caplin's friend, Lynn Alleway, to film what they thought was a record of the way the media reacts to people in the centre of controversy.
The resulting documentary, The Conman, His Lover and The Prime Minister's Wife, which was broadcast last month, did the pair no favours, with The Guardian describing Caplin as 'one merciless beeatch'.
'Carole Caplin felt her friend betrayed her with the documentary,' says MacLaurin. 'But unfortunately, neither Ian Monk nor myself knew anything about it until three days into the filming.'
However, as the mixed fortunes of celebrities in recent reality TV shows reveal, much depends on what the subject of a fly-on-the-wall documentary has to lose.
For example, from the ashes of a political scandal, Christine and Neil Hamilton used Louis Theroux to launch their career in light entertainment, while Channel 4's Jamie's Kitchen, helped celebrity chef Jamie Oliver shake off public cynicism and demonstrate his commitment to young people.
'If you've got nothing to lose and everything to gain, then fine,' says Max Clifford Associates founder Max Clifford, who has himself been on the receiving end of a Louis Theroux programme. Clifford claims to have played Theroux at his own game, spotting when the cameras were still running when they were supposed to be switched off, and using the programme to promote his business interests.
However, in terms of clients, he says the most effective way to survive a fly-on-the-wall is to get a signed agreement and take editorial control.
'No one will officially give you control, but there are ways,' he says.
These can range from the tricky business of negotiating trade-offs between both sides, to simpler tactics such as knocking the odd light or coughing when the interviewee is getting into obvious hot water.
Likewise documentary subjects can be trained to tackle any uncomfortable questions that programme makers may throw their way. For example, The Aziz Corporation runs a course called 'Interviewing to Death', where delegates are subjected to a barrage of the most outrageous questions an interviewer is ever likely to ask, then coached on the best ways to negotiate their way through potential minefields.
'It's a question of taking control over what you say and ensuring that things run seamlessly along your agenda,' says company chairman Khalid Aziz.
In addition, people can be trained to understand a programme maker's agenda, so that they know exactly what they are signing themselves up to. 'I think that people can get to quite senior positions in life and not understand the way a journalist's mind works,' says Weber Shandwick head of broadcast Peter Morgan.
He points to the recent Michael Jackson documentary as a case in point: 'Michael Jackson made the killer mistake of thinking that Martin Bashir was his friend, when their relationship was nothing more than a business agreement.'
However, fly-on-the-walls are not all about celebrities. Organisations ranging from Salford Metropolitan Council, subject of the BBC's A Life of Grime and easyJet, star of ITV's Airline have invited the cameras in to film behind the scenes.
Last summer, the British Transport Police worked with Films of Record on a four-part documentary Rail Cops for the BBC. The final episode was broadcast last month. 'The chief constable was looking for ways of raising our profile and decreasing the public's fear of crime,' says the force's media relations manager Simon Lubin.
With no editorial control over the footage, chief constable Ian Johnston encouraged his officers to view the exercise as an opportunity. He also reassured participants that the filming posed no threat to their careers.
The resultant programmes, showing officers dealing with drunk football hooligans on trains, youths playing on the track and the Potters Bar rail crash, produced a positive reaction externally and a more critical response internally. But Lubin feels that the overall package was worth the time, effort and resources.
Obviously with a film crew in residence for several months and some 2,100 police officers spread across the country, media training was not an option.
But Lubin sums up the best way to approach any fly-on-the wall documentary when he says: 'We had a clear objective of why we were doing it, we understood the risks and we had a good understanding with the film company.'
So, if you are involved in a fly-on-the-wall, don't go in blind.
In the hot seat PRWeek's Joe Lepper discovers what it's like to be media trained
As a print journalist, being quizzed by a counterpart from the broadcast media is not an everyday occurrence, but it's something I now at least feel reasonably comfortable with, following my half day's media training session.
For my afternoon at Countrywide Porter Novelli's (CPN) London base I've got four scenarios - live and recorded radio interviews and two TV: one studio and one on location.
The day starts with some handy tips to surviving a media appearance from my interrogator, ex-BBC man turned freelance Adrian Lort-Phillips and CPN trainers Jonathan Hemus and Nick Elliot.
The advice is plentiful, so there is much to remember. Avoid 'umming' and 'erring', don't waffle, don't rush and - vitally for TV - don't move your head. Many a company spokesman comes unstuck by an embarrassing likeness to a nodding dog in a car window.
The rules seem endless - avoid jargon, don't lose your temper, be patient, stick to key messages, remember examples, ask questions and think "location".
Before I start what is beginning to seem like an ordeal, I'm treated to a video nasty of media cock-ups. Reluctantly I agree not to mention names, but the utility boss who walks out of a TV interview and the company boss who promotes his exciting venture in an empty, run down workshop, know who they are.
Radio first. I'm taken to an office that looks a little like a radio studio where Lort-Phillips has taken the role of Fi Glover, asking me to comment on last year's Institute of Public Relations presidential election.
As soon as the first question comes, my mind goes blank. I look at this formidable microphone and my mouth disengages from my brain, which starts producing gobble-de-gook where reasoned argument should be. It starts really badly but thankfully gets better by degrees. Eventually, the soundbites start flowing and the answers sound crisper.
Back for the post mortem, where I hear the recording back. I already know the problems - a few 'ers' and 'ums' too many. But I'm also surprisingly lavished with praise. I may be in the guise of a spokesman but the cynical journalist suspects I'm being pandered to. Not so, I'm assured, but can it be a coincidence that my head is now swelling with compliments ready for my next session?
With my new-found confidence, I crucially remember to ask Lort-Phillips - now in the guise of a Radio Five Live breakfast presenter interested in PRWeek's take on Ken Livingstone - what the first question will be.
I also remember my key points, have examples, and the soundbites return.
But as I forget it's not live it's only by sheer luck that I don't drop any clangers that can be used for a 30-second comment.
After the second post mortem my head is now ballooning with confidence and I'm ready for TV.
"Don't nod" swims around my head in a rhythmic mantra. If only that same mantra could have included "don't look into the camera". Why does something as innocent as a peek at technology make me look so shifty?
TV, though, isn't as frightening as I thought. My two set-up scenarios were to comment on Jo Moore's indiscretion and then on a fictional Panorama report uncovering alleged corruption at PRWeek.
By the last scenario I was enjoying myself. The fear of the microphone and camera had gone, I'd stopped looking at the camera and I ended the day on a high.
If the aim of media training is to ensure you get your message across and appear like a confident, honest and decent sort of bloke, then I consider the day a success. There's hope for me yet.