With regard to bookshelves I have taken quite an interest in the tendency for folk speaking from home to position themselves with bookshelves behind them - such is my nature that the tidier the bookshelf the more suspicious I am of the speaker.
Not sure what my bookshelves would say about me, most books upright but with piles of books lying flat in front of them and all manner of junk shoved in around them! Tidiness is not a strength of mine!