Why would a book go gray at the top?

Question: Why would a book go gray at the top!?

Ok so I found some books I want to buy from Ebay because the condition is *Very Good*!.!.!.!.But in the description it also says

"Books look as though they got dirty!.!.!.!.the books are a bit gray at the top"

huh!?!? lol what would make a book go gray at the top!?!?

I would really like to know before I buy!.!.!.!.please answer!. :)

cheers,

XWww@QuestionHome@Com

Best Answer - Chosen by Asker:

Spotty grey probably is dust and water damage!.

Solid grey is probably either more severe dust/water damage, or it could have been bleached to grey by being in sunlight, possibly by being in direct sunlight on a bookshelf, probably top shelf!.Www@QuestionHome@Com