There are quite a few movies that I admire--on a technical level, as with something like Birth of a Nation or on a "achieved its goals" level--but do not enjoy. And calling them "good" feels like an inadequate word for the relationship I have with them. From a contemporary point of view, the propaganda of something like Birth of a Nation is less impactful because it now looks so over the top that it borders on parody..
I can't think of putting BOAN into my "so bad it's good" category because at least part of that lofty designation also depends on the movie being of no consequence, just some amount of brainless entertainment, accompanied by late night and beer.
Birth of a Nation, on the one hand, was a technical tour-de-force introducing audiences to one of the first Big Movies, but damn....what a way to do that. As I recall reading, Griffith, who grew up in post-bellum Georgia, claimed innocence, thought that it was all true, but there's no way I can believe that.
As a movie, it's interesting in its historical aspects, but after I've seen it, I always felt like I needed to go upstairs and take a shower to wash all that ham-fisted racism off of me. I feel somewhat embarrassed to admit that I watched that entire movie. That can never be a so-bad-it's-good movie, since I don't generally have to bathe after seeing something like Plan 9.