Are mirrors good or bad Feng Shui? Well, it depends. I rather you read on and be your own judge
Mirrors must be hung flat against the wall. It is vital to observe the kind of image reflected in the mirror. The image being reflected must be beautiful; do not reflect an unsightly or undesirable view as the effect of Sha Qi (negative energy) will be intensified.
Do not place too many mirrors in a room because the yang energy can cause confusion and lack of stability. Likewise, do not place a mirror where there is a direct glare from the sun or lighting. Clearly, drawing in good qi (energy) for wealth would be most beneficial; unfortunately, if you do not know the type of qi around your house, you could unconsciously draw in argumentative or harmful qi as well. So be attentive and make a note of how life is treating you before and after the placement of your mirror.
If you experienced difficulties or problems as a result of
1) A bathroom or toilet directly facing the front door
2) the bathroom or toilet at the end of the hallway opposite the front door
3) a bedroom and bathroom door opposite each other
or 4) a bathroom and kitchen door opposite each other
It is advisable to hang a mirror on the outside of the bathroom door.
Do not hang mirrors in a child’s bedroom because when waking up in the night, they are often terrified, and confronted by the image in the mirrors would make things worse.
Do not hang the mirrors at the foot of the bed or either side of the bed, especially for married couples. This would appear as if a third person is in bed, it is believed that marital problems would arise; and rather alarming leading to an eventual divorce. If you cannot remove the already installed mirrors, cover the mirrors with a drape or curtain while you sleep.
The Chinese people love to place a mirror near the dining table reflecting the food or a large basket of fruits as they believe this will “double” the quantities and bring abundance.
How about a Ba Gua mirror? A Ba Qua mirror always comes with green, red, and gold; the known auspicious colors. It must be surrounded by the 8 Trigrams originated from the ancient Yijing (The Book of Change) to reflect the excellence of Heaven. By the way, Ba Qua literally means the 8 Trigrams. It is used to hang exclusively outside a building, typically above a front door or any main entrance, where there is a source of Sha Qi (negative energy) directing towards the building or main entrance. Never hang a Ba Qua mirror inside a building or your home as it is believed to bring misfortune.