They get written up in the trade press and the mainstream media. They have grown far more complex: one film will now have multiple trailers, each specifically geared towards the youth audience or whomever the marketing men believe needs most persuading to help to turn the "product" - as most films are viewed by their makers these days - into a box-office hit.
Trailers have turned into a bizarre attraction all of their own, with the announcement of a hotly anticipated movie becoming an event every bit as momentous as the premiere. Previews of the new Star Wars movie, The Phantom Menace, had cinema-goers paying full price for tickets only to walk out before the main feature. Glimpses of a near-naked Tom Cruise and Nicole Kidman in Stanley Kubrick's final opus, Eyes Wide Shut, created much more excitement than the first reviews of the film itself.
All that trailers really lack, in fact, in these days of endless entertainment industry self-congratulation, is their own celebrity awards ceremony. And that gap is about to be filled, courtesy of an organisation called Golden Trailers, which is gearing up for its all-star inaugural gong show in New York next month.
"Trailers are where film-making and advertising meet. We realised there was nothing out there to acknowledge them, and decided it was time to give them some recognition," said Evelyn Brady, a former advertising executive turned film producer who launched Golden Trailers with her writer-director sister Monica and friend Esther Bell. "Everyone is always talking about trailers, whether they are good, bad, indifferent, give away the plot, or whatever. They are part of our commonplace chitchat."
The concept clearly struck a nerve, because in next to no time the trio managed to assemble a distinguished panel of judges, from Neil Jordan's regular producer Stephen Woolley, to an enthused Quentin Tarantino, whose own staff repeatedly told Ms Brady they didn't think he would have time for it. Hollywood may be overloaded with annual awards ceremonies - at least 200, according to a tally kept by the industry bible Variety - but Golden Trailers promises to be a little different thanks to the verve and humour of the organisers. Award categories include the Golden Fleece, for the trailer most likely to deceive audiences, and the Dark and Stormy Night Award, for the most cliche-ridden.
Curiously, the awards come at a time when trailers for mainstream films are being lambasted for their unprecedented sloppiness and lack of imagination. In too many cases, the trailer is not an incitement so much as a complete giveaway. Sometimes this is because the film itself is so unimaginative it has only two minutes worth of remotely memorable material to draw on. Sometimes, though, the marketing people have simply ridden roughshod over the film-makers' wishes, preferring brashness to any pretence at subtlety in their quest for the largest possible opening weekend audience.
Much of the suspense in the recent urban terrorism drama Arlington Road hangs on the audience's uncertainty about Tim Robbins's character. The producers, director and actors remained enigmatic on this point in their promotional interviews, only to see the game given away in the US trailer. Marketing won over artistic good sense, and the film's poor box-office takings may have been a direct consequence of that.
Evelyn Brady hopes the Golden Trailers will reinvigorate the artistry of trailers and bring them back to the standards of the Fifties and Sixties - an era when the knack was all in the tease, not the revelation. "We absolutely hope we can improve standards, and embarrass those who waste our time with bad trailers," she said. Any particular dogs she has in mind? The delightfully tactful Ms Brady is too polite to say.
The Golden Trailer awards take place in New York on 21 September.