You don't have to be an expert to express a useful opinion. You just hope that the person receiving it is adult enough to sift through it and find something useful in it, whether or not that opinion comes from the direct, "real" specific experience or not.
If a man was drowning and asking for help, I wouldn't think, well, hold on, I wouldn't dare to give you advice, not having been in that specific situation myself. So, I'll pass. Let me find someone who has nearly drowned before. They'll know what to do. Giving advice rooted in our experience is all we can do. Hell, it's all we ever do. Sometimes the advice is really bad. The good ones often acknowledge their lack of "real experience", as you put it.
I am married to a Chinese lady, have been through all sorts of Chinese-style tribulations over the past year and a half. But does this make me an expert? Hardly. This is my first marriage. I have no children. So if you want Chinese marriage advice, my "real" experience isn't that useful. Vince, however, is in a far better position to advise you. The roots of his experience are far more "real" than mine. Why? Well, take away the geography, and what remains? Someone who knows about people, who has been there and bought the T-shirt. I would take that every time over someone who says, 'Well, I've actually physically visited, so my opinion must be worth more'.
But, luckily, we have the luxury of a range of opinions here. People who've been to China and succeeded. People who've been to China and failed. People who've been to China and learnt nothing. People who've never been to China and know a lot about people and China. People who've never been to China and know nothing about people. People who went to China a while back and are out of date with the fast-growing culture. I've learnt from them all, and am glad I don't have to pick just one person's opinions to listen to.