I wonder whether coins would have been scratched only by those seeking to make sure the maid or boy, or even themselves, would not mistake the coinage at the market place, maybe, so would not be about deception, just about clarity, especially with other larger unmarked denominations around (even 6d's without roses, which might make you wary?)! I don't think a receiver would be taken in by a scratched cross, just useful to the bearer! I believe the scallywags would be more concerned with removing the rose from 6d's, and engraving them on half groats! I've seen two examples of poor rose engravings on halfgroats! Re J1 crosses, it could just be a matter of habit, following a quick weighing, until the 'old problem' had passed? Just speculation, but it really floats my boat in the absence of any historical fact!