You can go all the way through the data provenance: - do you have all the posters for all movies? Probably not. - do you have well-preserved examples of those

You can go all the way through the data provenance: - do you have all the posters for all movies? Probably not. - do you have well-preserved examples of those posters? Many are going to be sun- or age- faded. - do you have good scans of the posters that pre-date digital originals? and so on.