Horseshoes as wards? hell yes! I might as well have barbed wire fencing. 
I don’t get randoms.
It disrupts all unwanted energy, not just Fae. They are other enchanted with intention, but in his case they are physical too, as iron, like water, attracts electricity and disrupts magnetic fields. Energy beings have to keep their integrity to operate effectively, and this doesn’t hurt, it just bothers them enough so that they don’t like it avoid the area. Humans have the benefit of a physical body keeping everything in order so it doesn’t bother us.
I have have 4 used horseshoes I just found on ebay, I place one above the front door, 1 above the back door, 1 against the fireplace (the chimney is an entrance for the fae… ok the stove is iron so this one is more about adding gook luck and intention) and 1 above the door to my temple room (to keep things in).
I also place a railroad spike under my bed. This is not about Fae or beings, my house is built on an underground spring, and this dampens any subtle energy vortices produced from the water that could mess with my energy while I sleep.