Foreigner, or not?

Despite how you'd think it's obvious that I'm from the West, I'm continually baffled at how frequently that assumption is not shared by those that I'll encounter here.  Yesterday, while riding the bus to school (having jumped on after asking quickly in Bangla where it was going), the ticket collector asked if I was Bengali.  But not in a "yes/no" style, in a way that was like a confirmation of his idea that I actually was, as in "So, you're Bengali, right?"  I often wonder how people perceive me as I go about my business here.  It's easy to assume someone is a foreigner if they are wide-eyed and confused-looking and smiling all the time and just appear awkward and out of place.  But by now I'm so familiar with the Bangla I use all the time, Mohammadpur, and my routine transportation routes that I imagine I wear a face that's pretty similar to others'.  If you (being white) get on a leguna (mini-bus) and appear astonished and are looking around, others will giggle and start asking you the routine questions, as well as fit in a warm welcome to "our country."  If I am behaving like others, no one says a word.  That might mean it seems that I'm less interested in conversation, so they don't start one.  It may also mean that despite my appearance, the question about whether or not I am a foreigner becomes difficult to answer, and others may not want to risk insulting me if I were actually an albino Bangladeshi (which you do see from time to time).  It's quite interesting how life changes when you grow accustomed to a place.  Whatever the case is, the fact remains that people guess that I'm from places I wouldn't have imagined are possibilities.  Does that mean I seem more local when they ask if I'm Bangladeshi?  Or maybe does that mean that people run into foreigners so infrequently, their idea about them is so minute that you get the unexpected questions like "So, are you from China or Japan?"  The slum children who are rambunctious enough to toy with me will run up from time to time and obnoxiously bellow "Ching Chong Ching Chong!" in the most mocking way.  I usually freak out at them for that.  Not good moments for me.  They're obviously imitating the Chinese language when they do this.  Is that because they think I'm Chinese, or (perhaps more likely) they just think that this is the strange sound of a foreign language and because I'm a foreigner it must therefore be the language I speak.  Most of the time though they probably do have the assumption that I speak English, but the imitation is no less irritating: "I'm fine! Aeem faeen! Um piiiine!!!" (combine all three and you probably get the idea of what they are saying).  So then yesterday when I was at a restaurant eating lunch, the person at the table next to mine asks if I'm Iranian.  Then the waiter asks if I'm Japanese.  Then when I'm walking home that evening, three excitedly curious kids run up to me while I'm snacking on street food and one asks if I speak English.  I smile, sort of thinking it might be a joke, and then he intently asks again.  I say "Hae"(yes), and he turns to his friend and in Bangla says "See!  I told you!" Perhaps it's all a manifestation of struggling to figure out a puzzling addition to their community.  Sort of pioneering, isn't it?