keeping it kosher

I knew a Jewish woman in college who was very critical of our meal plan for not having more kosher options, and yet who thought nothing of eating pork chow mein when we were at a Chinese restaurant. Her explanation -- in total seriousness -- was that everyone knows that pork is kosher when it's at a Chinese restaurant. Perhaps there is a similar exemption for hot dogs; i.e., they're always kosher at a Fourth of July barbecue.