I would say both of these are a no-no really. Not just in China, but pretty much in any formal classroom setting regardless of nationality. Its a bit of a no-brainer to be fair.

In GACs, there are no assessments on the use of "f*ck" or "sh*t" words or on how well the student can criticize his/her local government, but shouldn't they know how to use such language when they are to study at a western uni?

I dont think there should be assessment of this nature either. Its kinda like saying should an American studying Putonghua be examined on how well he can shout down capitalism in L2 before studying in China?

However, that isnt to say you cant study or introduce informal language into the classroom, but you need strong and suitable contexts to do so. Informal language is best studied from looking at, or listening to genuine conversations. The comparison between the register of speech compared to perhaps academic or fictional English might be a useful tool for preparing students for real, native speaker speech too.

If you dont have access to genuine conversation, either recording or transcripted, maybe you could look at the informal language used in movies, TV, or music. Of course, being scripted, it isnt entirely natural, but could easily be used to identify informal language use. Maybe corpus study could be useful for that too? Concordance examples of 'like' being used as a verb or as a hesitator might prove interesting for some...although it could also be incredibly boring for some classes too! I guess ultimately, only you as the class teacher could really decide how useful such tools might be, and how important informal language, esp profanities, really is.

Generally .. I think most students I have met (in a training centre LOL) are exposed to enough examples of informal language through interaction with teachers in and out of class that specific lessons for such TL isnt worthwhile IMO. Five minutes here and there, or in an informal setting away from class is a better bet.

Language skills in being able to criticize, debate, argue, and offer opinion can be developed through 101 topics without having to introduce the issue of local politics, culture, government. I think its enough to know that some young people in some Western countries are openly critical of their society, you dont actually have to teach your students to do the same.

If you do want to raise political awareness ... I think you can do it without students really realising. Maybe you can have debate or discussion on something like Gibraltar, which I think the Spanish want back from the UK, but the Gibraltans dont agree...That could perhaps draw parallels with Tibet? Likewise, the Falkland Isles, which I think China dont recognise as being British, could draw discreet parallels with some countries not recognising Taiwan as Chinese? Im sure there are lots of examples like this which would be a far better bet than using Chinese political issues. Using Chinese examples is always going to sound like a teacher has an agenda to influence and persuade, which is always going to be a bad thing right?

Just my thoughts

Regards

NP