I ALWAYS lock luggage. Multiple locks for bags with multiple openings. When going intl from China-USA or vice-versa, I use TSA-approved locks. Between China-other countries, or domestically within China, I use any lock.

If you happen to travel without locks (or forget, as I once did flying PEK-BKK and leaving home in a rush), most Asian airports have some place near check-in where you can either have your luggage strapped or shrink-wrapped for a pittance, and I've sometimes had this done.