I think if you frighten the bejeezus out of them, you've succeed.
One year I carved a few dramatic jack-o-lanterns, placed them by the front door and put a red bulb in the entry light. When I heard one child out on the sidewalk plead, "No, mommy, I don't want to go up there," I reveled in the sweet sound of Halloween success.
Here's the scene:
http://wetracy.smugmug.com/Holidays/...32319128_HzS36