My take on mirrors is simple. If they are not placed in the right location, they may as well not be there. I do not follow feng shui rules of design, but I believe as far as mirrors are concerned, we should. Mirrors reflect the house back and they create space, therefore placing them incorrectly will create space in the wrong places.
The steadfast rule that I like to practice is to place mirrors where you want to expand a space. The traditional places such as above a hallway table, above a fireplace, above a dinning room drawer set, all these places are traditional for a reason and I believe these should be respected.
In addition, a mirror should not only be a design element but be functional and serve a purpose too. I believe that a mirror is placed in the right place only if you are happy to see your reflection in it and you are not taken by surprise. Any space that ‘surprises’ you with a mirror is poorly designed. Mirrors should give the effect of effortless flow of a room and not be forced as part of a design.