It is not hyperbole to say that this weekend could be a benchmark in the history of filmmaking. New Line is opening “The Real Cancun,” the first “reality” movie not based on a TV show. Along with Universal’s upcoming “The Quest,” it represents a challenge to the scripted status quo — but at what cost?From a bottom-line standpoint, the films cannot help but make money. Last October’s windfall for “Jackass” proved that films do not need a fictional narrative or much in the way of character development. There are no stars to boost costs or even necessitate a junket. The motto seems to be: point, shoot, distribute. Filmed over a few days on digital cameras and edited at warp speed, these new spring break pictures share some hedonistic qualities with old beach B-movies. But the raunch factor has been racheted up. In order to live up to the billing of “what you cannot see on TV,” breasts are bared and buttocks brandished. As unamusing as it sometimes is to see a brain-dead comedy ride the top of the box-office charts, there is a disturbing cynicism to this new spate of reality pics that goes beyond what the industry has thus far spawned: Getting participants to be exhibitionists on camera is one thing; exploiting them is another. Plenty may be gained financially, but principles may be trampled in the process.