I have been partner in two art galleries, the second one being by far the more successful, respected gallery.
My business partner in the second one was a great sales person, but also had a good art eye. Me, I've a non-sales persona, have never been interested in talking someone into a purchase, or a landscape design, beyond pointing out good bits if they showed interest. It was arguably a good pairing, with me being a painter and more laid back, and she being an enthusiast and sales closer. Not exactly good cop bad cop, but it tended to work with design clients and gallery customers.
If I didn't like a painting (among a whole show of an artist's work) I'd not push it, but I'd not knock it either. Sometimes a lesser painting (to me) puts others of the person's work in perhaps a better light, a kind of context. My associate would push something I knew she didn't like. On the other hand, that helped us keep food on the table. But, people like paintings for all sorts of reasons and memory connections, and if a person liked it, good.
If I or she truly hated something, we wouldn't show it, even as one among a lot better work by the same person.