Freedom of Speech is a valuable thing. So as an American, why self-censor? Of course there are ‘sensitive’ topics such as the Tiananmen Massacre, Democracy in Hong Kong, Rape of Nanking, Imperialism in the Opium War, Independence in Tibet and Taiwan, Diaoyu Islands, Spratly Islands, Ethnic Unrest in Xinjiang, Falun Gong, Pollution, 地沟油 you name it etc etc etc. Of course don’t practice Falun Gong in Tiananmen Square draped in a Free Tibet flag at dawn each day, but you get the point. There is beef to be found in China with everything. But this doesn’t mean you should shy away from talking about it. Anything in one-on-one conversation goes, unless they are from the PSB or the 青年团 so just use common sense. Many things are controversial but shouldn’t you as a foreigner open the perspectives of those you encounter in China? I’m sure your perspective on Tiananmen in ’89 is different from their perspective, so why not talk about it? Don’t engage in self-censorship because you are trying to be PC Politically Correct. Be the cultural bridge and a harbinger for dialogue.