There does seem to be different categories of scenarios. Young 20-somethings are often not bothered and teaching overseas still adds something to their career chances which are just beginning. A most comfortable type I meet is the older retired teachers or sometimes retired police or sometimes people who have an inheritance or business back home. Often a 55+ man. They aren't bothered if they return or stay. They aren't affected by anything either way.

The people who may not benefit are just as you describe. Maybe they are 35-50. Some divorced or some the type who found they were not getting ahead in life back home and so wanted something to "boost" their skills, experience and they are still young enough to look for a life-changing world experience too. This type often finds themselves staying a little longer. They are still young enough they are likely to find a long-term girlfriend or get married in China. They may even plan for 2 or 3 years.

You guys are right that this type often goes back to their home workforce and to their horrible surprise finds that they now worse off than ever before. It's almost as if they fell out of the loop. I've heard it described many ways but its like they return to learn the world 'moved on without them'. Indeed, they are even seen as 'dropouts'. As if they lost their place in the queue/line. I remember one describing the 1st question in job interview back in his home country was "Why did you give up working and just run away to China? Were you just tired of your job?". So you see the thinking! Instead of asking "why did you take on a big new challenge requiring so many new skills?" the local employer saw it as if he'd 'dropped out' and they see the 3 years in China as '3 missing years from your CV/resume'.

Again, this doesn't seem to affect a 25 or 30 year old as much. It won't effect an older semi-retired person at all.It does seem to work against that age group you described as 40-50 year old 'middle-aged men' and there's even that term 'economic refugees' which is not to say they don't have ANY money or opportunity back home but in a real sense get stuck inside a Chinese teaching career that in itself doesn't translate back home.

Someone else mentioned a good point about social lives too.. at that age these guys (and girls too) but they may often find a parent or parents had passed away while they were in China, family had moved, their old contacts had changed and when they return to their hometown all their 'social structure' and relationships are quite different. Adding to the all mentioned before.

*btw: I returned home after just a year. In that time my grandparents had passed away. Its a strange thing but somehow I expected to return to see my family the same as they always were but instead it was as if everything was so different. Another had moved away. The whole family world had changed and even stranger I came in almost like an 'outsider' in some sense (having gone through none of the year's events). Imagine 3 years!