Depends on, among other things, how much is known about the fabric in question.
If it’s new but the provenance is known then the reputation of the mill is a good place to start, I would think.
If it’s not new but the provenance is known then there’s an astonishing amount of advice to be found on the “Unfunded Liabilities” thread.
One of my top-ten favorite threads, in fact, though I don’t post there.
Whether or not this is 'objective' I'm not sure.
I'll be interested to hear others' thoughts on the question.