Thank you all for the thoughts. Brett, geosmin, stems, yeasts… difficult to pin down (indeed with some folks contradicting each other)… although I wonder if geosmin the driver or some of the other compounds found in this related article:
But I imagine intelligent folks will disagree (eg one experienced taster called the 2012 Meo Boudot very bretty on the nose, while another thought it was excellent… I just noticed a strong earthy note… that sometimes pops up in tasting notes described as ‘mushrooms’). I do like a note of earth in my wine (my spouse makes fun of me, “can we find you some wine with dirt in it” ) and don’t mind a touch of barnyard (which I thought would be considered a tiny amount of brett)… but feral wines that smell of sweaty animals are not my thing.