one 5second clip of amazing skiing does not make a good trailer, even an if the intire trailer is really amazing skiing does not mean it is a good trailer. the trailer needs to be edited well, (good song choice, edited to song, ballanced skiing vs. lifestyle, ext. ext,) A good trailer also makes you want to buy the movie, so far the only trailers that have really done that for me so far are Long Story Short, [photo]play, and witness. Show and Prove's trailer did not make me want to buy the movie it actualy made me want to never see the movie, It was one of the movies I was excited for but the trailer ruined it.
As for the best trailer I would say [photo]play.
For a really disapointing trailer would be ski porn, expected more from pbp.