Chinese compliments, Chinese tact

My friend DD just complained that - yet again - a Chinese taxi driver had told her something along the lines of, "You must have been pretty when you were young."

She was particularly shocked this time because it was a female cabbie; although, after so long in China, she really shouldn't be surprised to find that a woman can be just as insensitive as a man in commenting adversely - and very bluntly - on personal appearance, age, etc. And DD does rather invite this sort of vexation by goading taxi drivers to guess how old she is. She is in fact still in her mid-30s, wearing well, and a very attractive woman. Chinese taxi drivers almost invariably seem to estimate that she is at least 10 if not 20 years older than that. Perhaps they're just not very good at judging the age of laowai. Or maybe they're not very good at judging age at all. Or maybe there's some kind of cultural quirk here that they think it's more respectful, actually some weird kind of compliment, to overestimate someone's age. But they certainly don't seem to have any sense that they might hurt someone's feelings by telling them that they are "old", or "very old", or "too old" (or "too fat", and so on). Perhaps what the culture here is missing is a sense that it might be wrong to hurt someone's feelings in this way. I'm sure they must be aware that it can be hurtful: I once went shopping with a Chinese friend who was reduced to tears after a third successive stallholder had told her that she was "too fat" to wear a skirt she liked the look of.

I have suffered the same indignity as DD myself - the exact same insult, but in English rather than Chinese. Some years ago, I was approached by a young Chinese girl at a networking party. She pretty much kicked off the conversation with: "You must have been very handsome when you were younger." That attempted seduction ended right there: Mr Old & Ugly went off in search of a more appreciative audience.

In fact, I've heard this kind of thing so often that I wonder if it is an established Chinese idiom, perhaps something akin to "You must have been a beautiful baby". (Weeble, can you help us on this?) I wonder if it isn't prompted by the contorted sense of 'humility' in Chinese culture, which makes people feel uncomfortable if complimented directly.

There is still so much about this strange country I do not begin to understand.