Kuleshov effect: meaning is too contextual for metadata

Danah Boyd has posted an interesting rumination on the "Kuleshov Effect," wherein a still image is freighted with opposite emotions by adding different soundtracks to it. The most interesting question this raises for me is: how can we expect "accurate" tagging of the subjective content of an artistic work ("Happy boy," "Pretty dog") when there are such fundamental conditionals dependent on context?

Lev Kuleshov was a Russian filmmaker. Because of the political climate of Russia, he was left without access to actual film. Instead, he constructed films by splicing film and telling his story in a collage-esque manner. In addition to his style of film, he's known for something called the Kuleshov Experiment. In this experiment, an image of a man's face is shown juxtapositioned with various other images immediately following. Viewers thought that the man's emotion changed even though it is exactly the same shot.

Link