Of course we are all entitled to our own opinions and beliefs, but what are demons?
Demons are nothing more than negative energy. They're not even of this plane. You're not going to see hoofed legs and tails surrounding your bed if you think one is around. It doesn't work that way.
If you feel you have a negative energy following you around or in your home, do a simple sage smudge. Cast out the energies that aren't positive.
This can apply to other creatures such as faeries, angels, guides, etc. They're all types of energy. Types of energy that does not exist on this plane. It's going to be almost impossible to see a physical form of these creatures since they are forms of energy existing on another plane.