white spots to me are intolerable (crap on the neg when enlarging).

Black or grey spots can be dismissed depending upon location and type of image (crap on the neg when exposing).
  1. Black curlys in the sky--no thank you.
  2. Black dots in the pavement or trees--no problem.
  3. Black dots or curlys anywhere on a slick studio shot -- no way
  4. The same found in a still life like this or an image where content trumps craft or cleanliness-- no issues.