I had a bad experience this past December, as well, and this was on my 3rd tourist trip to China--this time to the Hunan area. I have a 10-year tourist visa but I was stopped at arrivals and taken out of the line and into an office where I was interviewed by two Immigration police. They first pointed out that my 1-year China tourist visa had expired. I then showed them the other page in my passport that had the 10-year unexpired visa.
This part of China apparently does not get many Americans and I rarely saw any westerners the whole trip--although it was off-season. The officers were rather hostile and clearly didn't know what to do with me and they started asking all sorts of ridiculous questions, like what college did I go to and what did I major in. Mind you, my college days were over 50 years ago!
Finally, after about a half hour, they told me to get back in the Immigration line but when I got to the officer at the booth I was taken out of line once again and sent to another office, to talk to a more senior official. There was also one other American that was having the same problem as me. This official looked through my passport again for a long time, made a call to someone else, and finally stamped me in. All in all it was somewhat scary as I was being treated like a criminal and I wasn't sure I would even be allowed in. I like visiting China, there are lots of places still to see, but I didn't feel very welcomed this last trip.