I really don't mind this sort of thing unless it becomes one-after-another, but I think a simple polite refusal or acceptance is the proper form. As for the appropriateness of the exercise, I think the form ("Hello my name is Joey I'm 7 I live in..." etc.) is a bit primitive, but the fact that real kids get to talk to real English speakers is good - all too many people in China have a nervous kind of feeling about 'foreigners' that is a result of bits of xenophobia in Han culture that stresses a 'They are REALLY DIFFERENT who knows what they'll do or say?' attitude, which often demonstrates or results in inappropriate this that or the other ('Welcome to China!' 'But I speak Chinese and have been here for 15 years.' Never mind, welcome to China!' etc. - after which it begins to be about face rather than real communication). Young kids, especially, can be talked to simply like real kids from anywhere, will respond to kindness even though it comes from a funny-looking guy whom they otherwise might be taught to fear as an ogre, and will be delighted. I really don't have much of a problem with this, unless, obviously, some parent simply uses you inconsiderately for a long period of time. The value of the exercise is not really in teaching method/learning more language, but in learning that people who look different and speak different languages are people too - as good a lesson as I know for people of any age, and a good one to acquire while young.

The ad is simply racist. There are historical reasons for racism, in China and elsewhere, which are very important to understand. Combating racism often (not always) demands patience rather than blind anger or self-righteous posing.

Most important, however, is to exterminate it utterly.

This is all very weird.

The dialects in Yunnan are difficult for me too, but I do not notice people refusing to speak standard Chinese when I politely point out that I can't understand dialect, unless they simply haven't learned standard Mandarin pronunciation, so the issue of what they 'should' do does not come up. And it is not simply a problem in China - people speak dialects all over the world. As for leaving people out of communication, this is often regularly done by the foreigners in Kunming whose Chinese is sufficient but whose mutual conversations in English are often carried on in many varieties of slang, which few local Chinese may be able to follow.

Everyone should come & watch the animal killed. Education is not all in your head. Vegetarians may abstain.