Because it works better going from bad to good.
Ugly:
I ate a bunch of total crap today. Thank you, ladytime. It was really terrible.
Bad:
I went over my calories for the day.
Good:
I *only* went about 300 over, which, all things considered, isn't terrible.
My weekly calorie average still was where it should be.
I finished my day with a healthy, veggie and whole grain loaded dinner instead of just stopping with my calories lower, but filled with terrible foods.
What are yours?