It's funny because about half of the Asian-descended people I knew well in HS actually were excellent at martial arts (I knew a few first and second gup in Taekwondo, a couple who were second-dan in Karate, and a couple who were competitive on a state and national level in exhibitionary Wushu). None of them ate dog, or at least not that they ever talked about, though.
And, ironically enough, I was often asked by some of the Asians to help them with their math homework, although one of the Korean-American guys was way above my level (I graduated HS with a 5 in AP Calc AB, him with a 7 in some really high level IB math), so he fit the stereotype pretty well.
Around here we have about 20% Korean-descended population with a good percentage of Guangdong-Chinese-descended and Vietnamese-descended, so what you have is more white people acting Asian than Asian-Americans being treated like they just stepped off the boat.