I have to disagree with this one. Why would the guy who sells produce buy an infinity plus one sword from me? I think having restrictions on what merchants will buy is okay, so long as, when you take all the merchant types into account, any item could be sold, as long as you were selling to the right merchant.
Good point. Let me elaborate.
I was really referring to the silly stolen items in Oblivion that could only be sold to a fence (I guess the merchants could tell by scanning the barcode, or maybe the magnetic sensor beeped on the way in, either way, very immersion breaking, get rid of it)
On the other hand, yes, produce merchants should, generally, only buy produce and so on.
On the subject, it would be cool to see an option to barter with
anyone, like in Fallout, in case they just happen to have something they'd like to get rid of in exchange for an item of your loot.