We had overall great experiences during a two week stay in August in and around China and Tibet (of course we made use of international branded hotels wherever possible, like Hilton, Sheraton, Holiday Inn, etc.).
That said, our stays in Tibet were a little more interesting - in Shigatse, our supposed four-star hotel had no hot water, a broken window, and no electricity throughout the hotel or the restaurant (though somehow our room did). It backed up to a Chinese military encampment that was busy all day long with marches and shouting and what-have-you. We assumed the hotel had simply turned off the hot water for the night and that it would be available in the morning. We were wrong.
I've never experienced such a cold shower in my life - turning the knob only made it colder. I must have looked like quite the idiot as I attempted to hold my breath while dousing my head under the freezing cold stream of water while attempting to maneuver my body to avoid as much of the water as possible. It didn't help that we were at about 13,500' up and I still wasn't well acclimatized. It was, without a doubt, one of the shortest showers of my life. The bathroom itself didn't look much better, and the toilet, while constructed to western standards, looked as if it had never seen a housekeeper's brush before. We were quite happy to leave that hotel.
Later that night, we arrived at Everest Base Camp to a spartan "hotel" which made our night in Shigatse seem quite luxurious by comparison. It wasn't a surprise - we knew what we were in for when traveling to this relatively remote place. There were some other interesting/fun experiences on that trip - some confusion over food and whether we were eating "potstickers" or "pork testicles", and fun and games with police and a taxi driver in Xi'An during the full solar eclipse.
I'll remember China fondly - not for its sophistication and glamour, but for its friendly people, most of whom want nothing more than to be gracious hosts. That and some of the crazy taxi drivers that nearly killed us...
