Watch out for students who want to practice their english in the Wangfujing area. I went to a tea shop with a young man who claimed to be an English student and wanted to practice (I'm a teacher). An hour & some tea & peanuts later, the waitress brought in a calculator and typed in our bill -- 560 kuai! I knew it was a scam the minute the waitress squeaked "dollar?" The young man was working for the tea house; he would bring foreigners in so they could charge them outrageous amounts. I heard a similar story from some Aussies who were charged 800 RMB (about $100 US) to see a tea ceremonies, again with english students.
I put 40 RMB on the table and walked out, despite the guy's protests that this bill would break his bank account. It was definitely a sketchy situation -- when has a waitress ever brought the bill on a calculator?
I've lived in china for a year and I love it here. Once you get past the belligerent yelling, most chinese are lovely people. Just be careful-- if something seems suspicious, leave!