Coffee is text. This statement is uncontroversial. Basically a look at the variety of coffee in varietal, flavor, or in cultures thereof provide a wealth of text to go over. But, since coffee is something that we have to understand through our sensorium, it also stands to reason that coffee is aesthetic. Again, this statement should be fairly uncontroversial since we understand coffee to be a matter of taste both sensorially and axiologically, i.e. regarding coffee's flavor and the value of drinking coffee to coffee drinkers. This understanding reveals a problem.
See, it's also obvious that none of this undermines some kind of platonism about coffee either, on the contrary we should be open to the idea that coffee is the kind of thing which can be described in terms of better and worse. This should be consistent with our experience of things like coffee. Indeed, as a culinary expression, we might even be inclined toward an understanding of coffee as more art-like than not. But none of this dispenses with a platonism about coffee. Notably, though, not dispensing with a platonism about coffee does not imply a relativism about it either. Nor vise versa. Accepting a relativism seems to merely move the problem I'm going to identify here down the line within respective relativistic theaters, however those might be carved up. Notably, by accepting an aesthetic nature to coffee, and I think particularly leaning toward an art-likeness one as well, it's not unreasonable to believe, per a platonism about coffee, that there is a best coffee. And again, this might be consistent with other works we know which share some of these features with coffee and may even tread in the arena of the sublime such as that may be understood for coffee or anything.
Nevertheless, while there is nothing inherently wrong with any particular culture of coffee, let alone one which bases itself on precision or empirical standards by which to judge a cup, I think that we can say that there is a misunderstanding to take umbrage with vis-a-vis a thus principled argument as is embodied in third wave coffee culture.
Being open to the notion that coffee is text, as should be obvious to any reasonable observer, and acknowledging even the possibility of an aesthetics of coffee, really leaves this kind of third wave purist open to the charge that the best in coffee cannot be measured empirically alone. Indeed I think that any presupposition beyond the fairly meager ones I've laid out here, especially those which seek to entrench coffee in an area irrespective of taste, do themselves a disservice and really lay the groundwork for their own reductio by eschewing any undefined or even ephemeral metric which may be relevant to some kind of unequivocal valuation of the aesthetic object which they cannot deny. Indeed, I suggest that, although inherently no better or worse than any anything else, evaluating coffee in any other manner than what encompasses the fully possible axiology comes with an inherent ignorance of the object qua an aesthetic object.
Third wave coffee enthusiasts have to bite the bullet on a relativism about coffee or they have to deny the possibility of interpretation on the matter and relegate their work essentially to a doctrine of engineering. Frankly I think they would be resistant to either avenue.