Yeah. Unfortunately, we have generally harbored much more negative, chauvinistic views towards unfamiliar nations and cultures.
Possessing colonial-era European cultural roots - which themselves grew in soil made from centuries of religious, class, ethnic, and nationalist in-group/out-group polarization and conflict - that were fertilized further through the "Indian Wars," and our nation's uncharacteristically kaleidoscopic ethnic demography, especially when compared to European nations. Those factors, and their influence on social, societal, educational, political, and other norms and standards, have molded us into a population far more sensitized to "in group" and "out group" traits than most other nations and culture groups, be they ethnic, class, occupational, religious, or national differences we may have.
Thus, when our citizens see portrayals of - for example - another nationality, or learn about that nation in our school system, or even when they hear a general characterization of their citizens, mischaracterized and laden with stereotypes or not - we are much more likely to internalize and construct our own mental image of those "out-groups" from all of those inaccurate depictions and impressions. Even when it's something demeaning, American citizens are generally far less likely to think critically about information pertaining to an "out-group," because the sheer fact that they *are* an "out-group," often blinds an individual to common sense, which is replaced by a notion of "well they're not like me, so I can't apply my own sense of what seems reasonable to them (even when one obviously ought to)." This manifested especially sharply in the 60s, during school integration, where white and black kids alike would often end up asking eachother ridiculous questions, like whether or not they would do commonplace things like use toothbrushes, eat simple and obvious types of food (stuff like apples), and other various "no duh" shouldn't-even-need-to-asks. That quite well depicts the level of "even though "they" may live literally a couple blocks from "us", work in the next building over from "us", be just as human as "us", need the same essentials as "us", and more - the fact that there's even a "them" and "us" to begin with, meant that "they"/the "out-group"/the "others"/the ones "not like us" may as well be aliens for all "we" know" that formed the foundation of our intercultural beliefs even up into the late 20th century.
It's that sorta crap that led to people asking you if you ate dogs, or came over to seek freedom, or if you're a communist. The deeply unfortunate inability to see beyond the stratifying traits, and to instead let all the misconceptions, stereotypes, incorrect depictions, etc. pile up and form the "knowledge" people think they have about new groups of people. While I'm sure it doesn't mean a whole lot, I do want to apologize on behalf of the midwits who pestered you with that nonsense.