Chinese Cosmopolitan Conundrum

I've been pondering this for a while now. Lend me your opinion.

What would you do if you frequently chance upon foreigners who take a condescending, stereotyped view of the East and disparage your culture or country UNKNOWINGLY?

Here's an example: You meet an American girl. She comments (with much finger-wagging and eye-rolling) "You know when I was in Terengganu? I sooooooo hate the way you people stare at me when I kiss my boyfriend. I mean, it wasn't like we were making out! It's just what couples do, right? And what about that horrible nasi lemak thing? It was so freaking hot! How could you eat something like that?"

Since you're intelligent, empathic, well-educated AND well-travelled, you immediately understand that she doesn't intentionally mean to offend. Her culture is one that encourages her to speak up and express herself, and so she's just giving her opinion on what she finds annoying. You know that she doesn't understand the pride locals take in their cuisine, and that the identities of both are inexoably linked. But you can't help but be pissed off that she's offending local sensibilities by kissing in public, and worse, she's insulting your food!

But you restrain yourself, and you hate it because you understand her culture intimately, and know for a fact that she didn't mean to cause the offence that she did. And you feel so geram that you can't just insult her back, because then you'd be as louche and unaccomodating as she.

Conversely, the moment you say something about real football being played not using the fake egg-shaped thing that huge men throw about on the field, she takes offence, going on about how stupid "soccer" is and how "people back home thinks it's a real dumb sport."

And therein lies my dilemma. Does harmony override pride? Where do you draw the line between "patience" and "doormat"? Does your upbringing and social grace dictate things, or do you allow yourself to ignore your own cultural references and take them on their own ground, using their own rules and logic? Doesn't that make you as uneducated and barbaric as they are? Or do you "do as the Romans do?"

Tell me.