I suspect that it's not just a language issue. But, it may be a communication, or cultural, issue.
For example, I know that when I have used one of the Asian languages with a native speaker and while in that Asian country (still working on my Spanish), I ALWAYS had to be careful with a concept called "face". It's a cultural thing there, and it is something like an "extreme" need to be shown "respect". We don't have that same sensibility in the western world. We seem not to be bothered by such behavior when it's aimed at us. (For proof, just read some of the threads on DR1.) But, in some of those places, in Asia, using the wrong words could cause a serious impact on your health.
However, it has been my observation (YMMV) that in many OTHER places, there is a heightened need to be shown respect -- more so than in many of the places we come from, and certainly more than what we sometimes show each other. In some cultures, that "respect" may be the only valuable possession that they feel they have had. The need for respect may then become part of the culture. And, if you - the speaker - is perceived to have more than someone, what you say may have an even bigger impact on them.
Just knowing the words in a language, but assuming that we can "communicate" as we do back home may never be enough. In fact, even back home, we may sometimes run into someone who seems to be "overly sensitive" to what we said. And we wonder why.
That's why people (expats) who live here, and learn about the culture, have such a huge advantage over those of us who do not. And why they will feel safer and more at home. They are learning what it takes to be part of that culture, not just what it takes to communicate. So when someone like Chip says "I don't see where my advice on using "stupid" is any different from anybody else post here - you just don't do it unless you mean to offend someone.", he may just know something that we don't.