I can feel an object and say 'its hot' on a scale of 1-10. The temperature is known. And I can do that multiple times, with some 1-10 scale, to get a sample. Then do that with multiple people.

You can then get a distribution of what people think is 'hot' versus 'cold'. What is icy, versus, bearable.

When you go to a doctors office and they ask you on a scale to rate pain, do you think that is completely bogus?

It isn't exact, but you can correlate between people. Yes, red heads feel more pain, there are outliers.

But a far cry from metaphysical.

The problem here is the word 'qualia'. Its just too fuzzy a term.