Seems solid enough for me.
About two months after my cat died prematurely and rapidly from a gall bladder gone bad, my daughter and I were standing downstairs and heard a very distinct and loud "meow!" behind us. Turned around and there was nothing and at that point we didn't own a cat.
She won't go downstairs by herself since then.
I'm not saying I believe in ghosts, but there is some weird shit out there.