A question about dubbing (re-recording voices in film).

I would like to ask your opinion on dubbing, please.
Some evenings ago I was watching a Attenborough docu on Giant Squids.
The scientist ‘chasing’ the squid (for decades, I believe) was a Japanese man.
He could understand (some) English, but (almost) couldn’t speak it.
So the documentary makers dubbed a voice over his.
They used a man that was also Japanese (or Japanese sounding) for that.
I had the idea that they let that guy talk English in a ‘wooden’ way (as if the scientist was able to speak English himself but in a ‘wooden’ way (I mean maybe put words in the wrong order, or small vocubalary).
Also, the guy whose voice was dubbed in spoke with a clear, thick Japanese accent.
What do you think of dubbing (in general)?
And what about dubbing in this particular case?