In message .com,
writes
I had perfect lined and painted interior walls.. until I decided to
remove a few marks by sanding over them then painting. On stepping back
to inspect I saw that you can obviously see the sanded areas - they
look like big patches of scratches to the lining, which they are! Any
ideas on a quick fix?

(Poly) filler and progressively finer grades of sandpaper

--
geoff