Worst anime translation or dub…hmm.
This has been said a thousand times before, I know. Mostly by oldsters like me. But guess what? You're gonna hear it again.
Warriors of the Wind.
This was the first official, commercial translation/dub of Miyazaki's Naussicaa of the Valley of the Wind, and it was butchered.
For those unfamiliar with it, almost a third of the film was cut. Not for time constraints, or God forbid, adult material, but for a plot element that defined the entire film. For a comparison, imagine a One Piece dub that eliminates Shanks from the story entirely. Seem like a bad decision? That's how the fans felt about Warriors of the Wind. Unsurprisingly, Miyazaki hated it too.
So much so, that Miyazaki has asked that English-speaking fans forget about this particular translation of the film; the same film that led to Studio Ghibli's very genesis.
For my part, I hope that it is never forgotten, lest such abysmally ignorant editorial decisions be made by so-called "professionals" again.
In recognition of Corsair King's excellent post, I will say that WotW was a commercial dub, and as such, was produced for a general, mostly American audience, in the early 1980's (CEO's Thoughts: "Hey, it's a cartoon; Cartoons are for kids. Take out this dumbshit 'intellectual' bullcrap and dumb it down to their level.") Editing and dubbing it in such a fashion made sense, from somebody's viewpoint. Unfortunately, it didn't eliminate two other plot points. Namely:
The lead character is a girl.
The lead character beats the ever-lovin' crap out of the soldiers who murdered her father, and winds up bloody and broken by the end of the film.
From a 1980's Marketing Executive's POV, this has zero chance of appealing to the kiddos. Little boys will be turned off by the fact that the lead character is a girl. Ooh, cooties! Yuck!! Little girls will be turned off by the horrible violence. It's not shiny, pretty ponies leaping over rainbows! Wah, Mommy I don't like this film!
Which begs the question, what target audience was Warriors of the Wind aimed at? A general audience over the age of twelve could have followed the unexpurgated plot. It just seemed as though too many executives passed decision on what the dub should be, and wound up ruining it. As I recall, it never was a big commercial success either way. So in the long run, it was a bad dub because it failed to make a good return on investment.