On a Shanghai-Narita flight earlier this year, Mrs. Yogimax and I were both upgraded. The boarding passes were already printed and waiting at the counter so it had nothing to do with appearance. I'm actually quite glad because I certainly do not appear to be a platinum elite in the way I dress. Just as an aside, though, I have noticed priests in clerical collars sitting up front. Who knows, though, if they were upgraded or travelling on a paid ticket.
From the responses so far, as well as personal experience, it looks like the "easiest" international op-ups are the feeder flights into Narita