Does reputation influence what I can sell?

I have a Wand of Lightning, a Red Potion and a Violet Potion in my inventory, but I can't sell any of them in Nashkel or in Carnival. I believe I sold the potions in my last run. Could my problem be caused by my low reputation (8)?

EDIT: Eh, sorry. I just sold the potions in another tent that I missed. But I still can't sell the wand. So I'll rephrase my question: are there any simple rules to this? What makes some things vendible in some place and invendible and not vendible in others?

If the wand is used up, I don't think any vendor will buy it.

When a wand is used it, it simply disappears. A good way to keep it charged, is to sell it and buy it back from a merchant.

As for the rules - it just varies from merchant to merchant.

Each merchant has its own buy list. So smiths will buy weapons and wizards buy magic related stuff. But, there are no strict rules, strictly speaking these are just guys who devs allowed or disallowed to buy stuff, its not based on any ingame mechanic.

Also most merchants won't buy stolen goods

Ive found that one particular merchant buys almost all sorts of goods off of your character, and thats Ederne (spelling?) at Durlag's Tower. Try him.