In Risen, when you got to the Great Swamp and to merchants/traders, the UI for it was a little confusing for me.
I couldn't tell if I could sell junk for gold, because the amount of gold never went up. And for some reason when I tried to, a message would pop up saying YOU WILL RECEIVE THIS AMOUNT OF GOLD, but didn't read it for some reason and quickly closed it thinking it said something like I was getting the short end of the stick.
So I'd gather a bunch of useless shit (monster teeth, weeds, whatever), offer it to the trader and then get what I needed, I was actually trading with them instead of buying and selling.
Gold was hard to come by, only through quests and stuff. Everyone always mentioned how poor the village in the Swamp was, so I thought thats how things were. It was actually quite immersive for the poverty atmosphere. Some guy was selling armor for 700 gold. Gold only, no trading. I was like HOLY SHIT THIS GUY SUCKS. I basically did the whole swamp segment in my ship wreck clothes like a poor man should of, slowly saving up 700 gold pieces.
Then I realized I could sell anything I want for hundreds of gold. Ech. I liked it better the other way, grinding otherwise.