I'm going to begin with a ragbag genre that already predominates on Sky and is rapidly colonising terrestrial channels. I'm talking about shows such as Police, Camera, Action, hosted by Alastair Stewart.
Say what you like, Police, Camera, Action is 100 per cent true real life, as it happened. So we can trust the realistic world that Alastair leads us though. A world where the police have a 100 per cent clear-up rate, where every police driver shows perfect judgement and every car-thief is a crap navigator who immediately turns down a cul-de-sac, where every crook in England has his own police helicopter hovering permanently over him, and where every speeding imbecile who flips his caravan over is, in Alastair's catch-phrase, "miraculously unhurt" - so we don't have to feel guilty about having just enjoyed watching a car crash.
Now, I know Alastair gives us his road safety tips, but do we really need to be told that it's a bad idea to cycle backwards up the M11?
There's a similar real-life-as-it-happens show called Eye Spy, presented by Selina Scott.
One item I remember was a very-long-distance black-and-white night-time sequence of a car being vandalised by "youths". Absurdly, at the end of this screen-filler, the indistinct face of the culprit was hugely magnified, till it had become an electronic splodge that looked like the Elephant Man's younger brother, and Selina said: "Do you recognise this man?"
What's most striking, I feel, about these secret camera shows is their laziness. They just compile unconnected snapshots - there's no story. Hardly a thought goes into making or watching them.
The same could not be said of the docusoap. At its best, it's a form that's addictive for viewers and schedulers alike. Y'know - "It's Monday morning and there's more bad news for Jeremy Isaacs. The new production of Aida is pounds 4bn over budget, and the Opera House is on fire."
It has produced a fascinating insight into how institutions work, or don't work, and it has given us characters such as the irritable Keith Cooper. And here lies the pulling-power of these series, the characters, whether they're camp and lovable, like Jeremy in Airport, or camp and punchable, like Ray in Clampers.
But this summer, of course, the entire varied genre of the docusoap was dragged into a massive controversy. The makers of Driving School admitted that they had "re-created", in daytime, the scene where Maureen wakes her husband up during the night so that he can test her on the Highway Code, after Maureen had told them about just such an incident.
Re-enactment isn't a new technique, either. In the Fifties, there was a wonderful nature documentary which included a stunningly balletic slow- motion sequence of migrating lemmings leaping off cliff-tops into the sea. But we now know that these "wild lemmings" were in fact pets, previously purchased from Eskimo children, which were then booted off the cliffs by the camera crew. Now, I know a lot of people will be thinking that what I've said is the usual bleat from snobby, patronising writers who hate people's television, that I'm basically an elitist. Well, it doesn't bother me when people call me an elitist; I just quote Racine at them.
But I have to say that in my 22 years in TV the most snobby, patronising statements I've heard have all been made by self-avowed populists. The truth is that TV invariably wants the reality of ordinary people on its own terms. They're the raw material, not part of the manufacturing process.
And no show mines this material more hungrily than daytime talk shows. And the king of the bear-pits is Jerry Springer.
The slogan on Jerry's office wall reads: "No subject too indecent, no individual too pathetic." Well, human patheticness is an infinite resource. This is the genre that I think can least be trusted with real life. It treats people as human Plasticine: malleable, disposable.
Huw Weldon said that "above all, TV is a place to tell stories". But there is a difference between observing life and just feeding off it.