For example, whenever I watch an American movie with Japanese subtitles: the translation kind of sucks since there are words translated literally word by word making zero sense or lack of taking account of visual context from a scene. Depends on who translated the dialog, it could be that translators didn’t watch the movie or understand the context in specific scenes.
I recall watching Clear & Present Danger (Harrison Ford) with JP sub, there was a piece of dialog where the commander of a special forces unit gave the orders on planting explosives in which he ordered them to “cook it” basically implying on detonating the trigger but the subtitles translated this as 料理しろ which is incorrect when you account the scene’s context.
Whether you speak German, French, Spanish or etc. are the translated subtitles crap when it comes to movies where colloquialisms (slang), jokes (humor) or wordplay (puns) are thrown into the mix while listening to the original English dub? It’s because subtitles only convey a message but can miss nuances from spoken dialog via the source language.
My country allowed foreign cinema “only” with subtitles because most of the population was illiterate and the idea was to keep viewership of such media low without resorting to very harsh censorship, although it existed at the time.
It backfired so bad the general population developed a knack for acquiring foreign languages, through those media. Being a latin language country we score very high on the domain of english as a foreign language. Many of us also speak a bit of french and a large majority knows at least how to curse in spanish to return the love.
It was a common recommendation when I was a kid to expose children to non-dubbed media to develop foreingn language and reading skills.
And I can personally vouch for this, as I started developing basic english domain very early through cartoons and movies and the need to follow the subtitles helped me develop my reading skill and speed.
Regarding the quality of dubbing, I can only say something always gets lost in translation. More recently, I’ve followed a couple of series, both subtitled and dubbed, and the end result is completely different. Subtitled, you can follow the emotions in the original actors voices and postures. No lag, no difference, no adaptation. Dubbed, it often feels like watching a completely different show. And the voice over actors are professionals, obviously. But it is common for the voice over team to take some liberties.