Oh for heaven's sake - there's no way any farmer wouldn't be aware that this was being done to their flocks. Does anyone have any idea of the time this would take? Sheep having to be grabbed, thrown or stocked, & then sprayed? Good grief. Definitely some marketing gimmick that the farmers are in on & most likely did themselves. Shame about the fleeces, but it's quite possible the ink used was the same as used for ram markers, in which case it should wash out.
The farmers probably got paid more for the advertising than they would have for the fleeces! Or they threw it in with the belly wool after clipping the paint out...it wouldn't be that hard to shear around it.