I've been spending a few months around Vernis, diving into the Puppy cave over and over (and over and over...). When I come back, I sell all the loot to the shopkeepers. Most of it isn't useful to me, and some of it is quite valuable.
So I more or less sell everything to the baker ("Here, have a Spellbook of Teleportation! What do you do with it? I dunno."), until he runs out of cash, then the Innkeeper ("I have this doomed breastplate I don't want. Give it to your cat or something."), and then on down to the General store clerk and the Magic vendor.
One thing I've noticed is that these shopkeepers don't really like me, and I don't know why. The baker, especially, hates me. Still lets me shop, but seriously hates me. The innkeeper finds me annoying, and the other clerks are definitely trending downwards on the likability scale. It doesn't look like they pay me less for my items, but I might be wrong about that.
Why is this? Is it because I'm treating them as convenient useless loot repositories, with no regard to what they actually sell? Will they stop buying my pile of junk if they hate me enough? What can I do to make them like me more? Is there any use in trying to make them like me more?