NEW YORK It's not a Budweiser commercial, nor is it a Super Bowl contender. So the not-so-pretty sight of a horse's ass interacting with an average American family, wagging its tail and dominating scenes with Mom and the kids, is, well, not exactly classy. In fact, it's sort of shocking. Especially when it turns out that the spot, "Horse," is part of the first Sony Electronics campaign from BBDO in New York. All becomes clear thanks to a title card that says, "Your dad's not a horse's behind." (Wonder how many iterations "horse's behind" went through before it was approved?) Indeed, it's a clever and attention-getting way to sell "face detection," a Sony digital camera feature that ensures faces (not background images) stay in focus. If "face detection" is the brief, we get it, with both a carrot and a stick. Those views of the equine hindquarters stay with you. It's not subtle, but it sells.