I have heard that animals and young kids can see ghosts because they are more opened minded then older humans...
My cats don't mind the ghosts in my house. (Yes, there are ghosts in my house.) Whenever I take pictures of Snow or Angel I can see blurrs and human-like figures by my kitties. CREEEPY! I also hear footsteps in the middle of the night and the temperture drops. Whenever Snow feels this, she runs out in the hallway or where ever she can see the ghosts.
I think my cats like the ghosts. I mean, they cant hurt you or anything, only scare you.