At present black wool is worth more than whiteYes that is correct to a certain extent
Any black must be called and the rousie picks it out, and it’s thrown in the bin or down the porthole. A fleece with any more than 3 or 4 black spots is discarded. Animals in stud flocks are definitely marked for culling, in commercial flocks it depends on the farmer.
As an aside, some rousies would have the black wool picked out before the shearer called, Johnny Kirkpatrick’s daughter was one of them.