Let's get this started again.
Mirrors can be good or negative depending on how you use them.
One place you do not want to use a mirror is in the bedroom, especially if you can see it from your bed. The reason for this is that it can pick up on the smallest amount of light. If you wake up during the night you might see a reflection that startles you. It can be a reflection of yourself, a blowing curtain or a pet walking by. No matter what it is if you are startled while sleeping it is sure to affect the rest of your nights sleep. Without a good nights sleep your whole day is affected.
Have you had an experience with reflections in a mirror? Tell us about it here.