I am not a native speaker, but I noticed that in Australia people sometimes replied to the question "Do you mind...?" with "Yes", actually meaning "No" (they don't mind).

It happened enough times so that I've asked a few people why they were replying "yes" instead of "no", to which they couldn't give me a clear explanation. This really surprised me at first, but then I understood that the words didn't matter as much as the tone of voice.

Is that something common in Australia? Or in any other country? Or was that only a non-representative sample that happened to make the same mistake?