Why Are Dead People Liking Stuff On Facebook?

I am not convinced by the explanation from the Facebook spokesperson. I am an active Facebook user and I am not a basketball fan but there have been atleast 2 or 3 instances where I noticed that I had to "unlike" the basketball page and I have no recollection of "liking" the page ever.

I don't follow basketball so its very unlikely that I would find its Facebook page and "like it".