I'd expect those kinds of comments from children. Little kids seem to ask silly questions that might embarrass all the adults in a room. Children lack the social knowledge that would stop such a question from being asked. I would think as adults people would grow out of it, but that doesn't seem to be the case with many. It just seems like common courtesy to not ask such questions or make such comments until you know the person is comfortable with them.
I've been thinking about the allusions to children in this thread, and I've been thinking that maybe we (the quiet ones) are still kind of like children in some respects. This might not be the case with everyone, but I know I pretty much grew up hearing things like "children should be seen and not heard," and a child's lack of social knowledge about what's appropriate to say may make this a valid rule to follow.
But maybe some of us were never coaxed out of this mindset, and perhaps still lack the social knowledge about what's appropriate, or even if we do know, we're still afraid to speak our minds- another saying comes to mind, "if you can't say anything nice, don't say anything at all," which could be taken to an extreme, as there are times when things need to be said that aren't necessarily "nice," or just the fact that different people have different sensibilities, and we may be afraid if we think that anyone
might possibly take offense or disagree with what we have to say.
Then of course there are the adults who aren't afraid to speak their mind, but still apparently lack the social knowledge as to what's "appropriate" to say- or again, it could just be chalked up to differences in opinions about what's offensive and what isn't.