Subs are generally the way to go, but in certain cases there are films where the "original language" is not so cut-and-dry one way or the other, e.g. many Italian genre films (Gialli, spaghetti westerns, etc) where English and Italian audio tracks were each recorded during post-production and attached to the prints for release in their respective countries. This is also true for a few of Herzog's movies and I'm sure others as well. In these cases, English dubs are acceptable if not downright preferable.
