An unpainted head comes to the shop as an essentially white casting, with ultra-realistic glass eyes pre-set. We prep the head to insure our laquer-based paint will readily stick, and then begin the painting process. When we've finished, we clean the eyes of overspray and let the head dry before spraying a sealer on it (normally about 24 hours post-painting). It's amazing how a decoy head "comes to life" once the overspray has been removed from the eyes - another reason why full-mount decoys are so much more realistic than cheap plastic birds.
If you have any artistic ability, you might want to give head painting a try. If nothing else, you can use an airbrush to repaint the heads on your plastic deeks. After all, plastic decoys are mass-produced, which means they are "fast-produced", and in the overseas shops that most deeks are made in, quantity, not quality, is the objective.
After all, if you were a wary old gobbler (or hen), which one would most likely fool you?