In the world of nutrition, I find the biggest issue with consumption is portion size! Almost every food (in my opinion) can fit in a healthy diet--the trick is to find the proper portion and to enjoy these treats in moderation!
Ideally, snacks should be kept between 100-200cals. Now, of course I would rather you choose a nutritious apple & yogurt for about 120cals vs. a 100 calorie chocolate bar; however, we all have to be realistic! The closer you stick to eating what you want to be eating, the more likely you will be able to achieve success with health! The goal then, is to enjoy our "treats" to help keep us sane and on track, but keep them within reason.
Most mini-chocolate bars treats are about 70 calories--have 1 or 2 and you are well within the 100-200 calorie range for a healthy snack. Have 8 a day, and all of a sudden you are past the 500 calorie mark. Do that everyday for a week ---and you're gained 1 pound of fat.
So...the Halloween "Trick or Treat" solution....is to remember "Portion and Moderation!"