I got stung at a Spink auction as well @VickySilver. I bought a group of halfcrowns, including a 1925. It was partially my own fault as they did not show the obverse of the coins. Most were ok but the 1925 had a light X scratched on the bust. I took it as a lesson learned. It is a shame really as the 1925 is a very high grade, scratch aside.
It is a shame so many of the DNW coins are cleaned but I am glad they have flagged it before the sale.