Recommending books feels like a dangerous business. Once you embark on a conversation about fiction, you don't know where you might end up or what might be revealed. Will your own knowledge be found lacking? Will you expose your own tastes to criticism? Will your recommendation be seen as an endorsement of one book over another? In this situation, the temptation is to play safe by suggesting something middle of the road.
Recommendation is a loaded term. If we look at parallel situations, staff don't feel they carry responsibility for a customer's choices. If you go to buy a new outfit, you can take three items into the changing room; the assistant hopes to sell you one but she doesn't feel implicated by your choice. You try on a lot of outfits before you find the one that's right for you. It is just the same with books. You can try a lot of books before you find the good read you're looking for.
There is no stigma or sense of failure attached to not finishing a book; it's not your fault if you don't like it. If you decide an item of clothing you've chosen doesn't suit you when you get it home, you don't feel there's something wrong with you. Nor do you blame the assistant who served you.
How can we feel more confident when suggesting what the borrower reads next without feeling personally implicated?