If you frequently drive around clients in your car, you have to be careful not to leave every self-help book you happen to be reading in plain sight in the back seat.
Clients sitting in the back seat will notice them even if you tell yourself “Oh, they probably didn’t see that.”
And they will either make an unflattering assumption about you or ask to borrow the book from you. Neither of which is desireable.
It is much better if I client finds out about the self-help books you are reading by you posting pictures of them on Facebook. That way they won’t ask to borrow them. And if they make a snarky remark to you about what you are reading, you can tease them about still being on Facebook at their age. (Of course, they might find that comeback from you ironic and buy you a few more self-help books.)
And if all else fails you can tell them you bought the books to help you learn better how to cope with them. That is a good line for saving face–and losing clients.
It just makes better business sense to talk about the weather.