This gets bandied about a good bit by New World winemakers: all Brett tastes the same. And, you know what, I think they're right, at least when it comes to New World fruit. I've yet to find a Bretty American wine that tastes like anything other than band-aids and medicine with the occasional bit of screechy acidity.
Yet when it comes to Old World Brett-bombs, the aromas tends towards horse sweat and straight up barnyard, though these often seem to have elevated acidity as well. The question is, what is driving this different expression? Is it a different strain of Brett? Or are different nutrients in the must or finished wine leading to different expression? Or is it just a byproduct of my own limited sample size or even my own internal biases?
Regardless, I side with the California winemakers who view Brett as a pest. It masks varietal and regional expression. This is only a wild, unfounded hypothesis, but I suspect the higher sugar levels in New World fruit as well as the carbohydrates from new oak provide the fuel for this monolithic sort of Brett expression. While Brett is rather common in 'dirty' Old World wines, the limited use of new oak and lower sugar levels likely limit or alter what Brett produces. It'll suffice to say that I'd love to see a systematic study of 4-EP and 4-EG (Brett byproducts) levels for a variety of starting conditions such as Brix, varietal, and so on.
In the mean time, New World and Old World, don't stop what you're doing. I'll look for something clean from the New, and something dirty from the Old. Dirty New or clean Old just ends up being boring.