PERSONAL: ordering book displays

I'm volunteering at a charity shop for a few days. I started today. The books were on offer because a lot had been donated. The most striking thing for me was that they were displayed according to colour. Part of me was horrified (they aren't clothes!), but at least there was some order. I've been to shops where books of all shapes and all sizes have been lumped together. It's annoying because it looks like a mess and if you're dedicated/obsessed enough to go through them all or if you're deluded by the chaos to think that there's the possibility of finding treasure, you have to go through them all with nothing to guide the eye. Usually, it's a long and frustrating process. I don't love alphabetic systems in shops however, it takes the romance out for me as a book searcher. And it makes for odd companions. I suppose my preferred method - in shops - is themed books: literary, murder mysteries, adventure, westerns, romance, children with books perhaps ordered according to size.

Let's not discuss my personal system, which is a work in process, dictated by shelving space and half my books not being to hand or unpacked. But then, I'm not trying to sell them.