I'm interested in your opinions of how foreign-language films and TV programmes in Poland (nearly) always have a man's voice translating the dialogue.
Not always. Sometimes they use a woman's voice.
Is there only one narrator in the entire country, or are there many identical-sounding ones?
Like I said, they need at least one woman too, so this interesting theory has - unfortunately - failed :)
If you're learning or practicing speaking English, do you find it gets in the way?
Not as much as if they would make the dubbing, you know :)
Do you like it or do you hate it?
Hm. It's not that I love it, but if I have the choice between narrator and dubbing I'd go for narrator. Because Poland has no tradition of doing them so when it is done then the results are (usually) bad. As for narrator you may believe me or not, but when done properly somehow his monotone non-emotional voice is mysteriously mixing in your brain with the original voicetrack, making you feel like listening to the original voices but speaking everything in Polish. In other words - yes, it works.
Of course, when I can choose subtitles I do it, but sometimes, usually if I am very tired and don't want to concentrate on reading too much I prefer narrator too.
Do his smooth tones turn you on
No, they doesn't...
...even on the dullest of documentaries?
...neither in narrated porn :D