As long as I can remember, I have been sticking my nose into any book that I am reading so that I can smell its pages.
I suppose that in brand new, recently printed books I am smelling the paper and the ink. Books printed in different countries often have distinctly differing odours.
As books get older, the smells of their pages change. This is both the result of ageing ink and paper and also a consequence of the environment in which the book has been stored. For example, if the book has been housed in the shelves of a reader who smokes, the pages acquire a tinge of the smell of tobacco and its smoke.
At first, I believed that I was the only person who sniffs the interiors of books, but now I know that I am not alone. The world of book readers is divided into page sniffers and those who do not poke their noses into books for reasons other than reading.