The key to the Dust and Scratches filter (Filter > Noise > Dust & Scratches)is that you want to keep the Radius as low as possible and the Threshold as high as possible.
I actually saw a video “the other day” about this filter, and found it very usefull and easy to use when repairing very old photographs i am scanning for preservation and webpublishing,
And go back and mask back in the things it thinks are scratches in digital images
Great suggestion Bryn! Otherwise you might loose important details like small catch lights etc.