Trailers have received scant attention from film critics; Lisa Kernan's peppy 2004 history of the genre, Coming Attractions, is one of the rare exceptions.

This is probably because the trailer is not considered a 'pure' genre. Trailers exist for one reason only: to make us go see the film.

But they differ from other forms of advertising in that they are made of the same stuff as the thing they're selling. This is probably why trailer designers find it so difficult to get away from the product.

Few ad men would come up with a TV perfume commercial in which we spend 30 seconds looking at a bottle of perfume from different angles, and yet this is what movie trailers usually do.

There are exceptions. Orson Welles turned the Citizen Kane trailer into a jaunty first-person preview in which the director/star nonchalantly conjures up his cast for interviews, and suggests, in his effortless manipulations, the heady dangers of the lure of power that is the subject of his film.

And Alfred Hitchcock's trailers made the sly avoidance of the film itself into a trademark: in the Psycho preview, for example, he took his audience on an avuncular tour of the Bates motel and house, pulling back the shower curtain right at the end to reveal the screaming face of Janet Leigh.

More recently, the trailer for the Jerry Seinfield film Comedian featured Hal Douglas - who vies with Don LaFontaine for the title of the most famous trailer voice in the business - being berated for laying down a voiceover track that consists of a string of trailer cliches such as: 'In a world where...' and 'One man...'. All the audience learned about the film was that it was 'a film about comedy with Jerry Seinfeld'.

Miramax could get away with this because Seinfeld has such a huge fanbase. More common is the trailer that begins as something else but then segues into a more conventional series of edited highlights (Eternal Sunshine Of The Spotless Mind, Toys).

I like a well-honed classic trailer as much as the next man (Juno and The Bourne Ultimatum are recent favourites).

There's a certain purist satisfaction to be had in watching a trailer that keeps external devices such as voiceover narration or captions to a minimum, stirring expectation and desire purely though clever editing and sound design.

But we still seem to be stuck on the concept that the trailer should somehow be a microcosm of the film, displaying the most striking scenes or snappy one-liners the same way a canny salesman might lay out his best carpets on top of the threadbare ones.

This is why I was so intrigued when I watched the first theatrical version of a trailer for a disaster movie that didn't even have a name. It consisted of home-video footage of a party in a New York apartment, which is suddenly thrown into a chaos by an apocalyptic firebomb attack on the city.

Panic stations

There was a real sense of panic and abject terror about this teaser, and though clearly fictional, it felt authentic in a Blair Witch Project sort of way. The best thing about the teaser was that it consisted of no more than the first five minutes of the film: a fairly radical defiance of the prevailing convention.

In mid-November, Paramount released a second trailer, which among other things revealed the film's name, Cloverfield. But for the viewer, the new trailer came as a disappointment.

Visually, it still looks promising, but now the outtakes stretch into the second act you can make out the bones of a fairly conventional monster movie. The teaser was edgy; the second trailer looks more like a hand-held War Of The Worlds (not a compliment in my book).

At least the second version is more honest. But however Cloverfield turns out, it's extremely unlikely the teaser will have actively misrepresented the film. All it will have done, compared with version two, is left a lot more to the imagination.

If other forms of advertising work unabridged, then so can trailers. Sometimes the greatest-hits approach works, but just as often, less is more.