Sounds like Celestar340 has identified my problem: the issue seems to be regional vs. long-haul meal service. Since BKK-HKG is only ~2½ hours (1,063 miles) each way, they may well be better on longer flights (trans-Pacific, or to Europe).

And doc, I would have preferred a bad dim-sum meal - at least I could keep trying different dishes in hopes of finding something edible!