Elves always annoyed me before I learned that it's far simpler to just sieze their goods then murder them.
It'd be like
"Ah, welcome to our humble fortress! I see you have brought your *ahem* usual inventory."
"Yes, we carry only the finest in Elven -(rope reed cloth)-, and these five Wild Strawberries. May we interest you in any of our goods?"
"Ah, well, we are running a bit short on cloth. Perhaps we could barter over, say, that bin there... and that one... and the one there."
"Wonderful! And what are you prepared to offer in return? Our druids were delighted by the unique and complex stone crafts you offered us last year. Perhaps we can expect more of the same?"
"Of course, of course! Urist, bring the stone crafts here, that's a good lad. Now I'm sure you'll take note that our craftsdwarves have only become more skilled since last- what? What's wrong?"
"THOSE GOODS ARE BEING CARRIED IN A WOODEN BIN!"
"Ah... ah, well, if it's the bin that bothers you we can just as easily-"
"NO! ABOMINATION! BUTCHER OF NATURE! THE MOST VILE OF CURSES ON YOU, YOUR FORTRESS AND YOUR KIN!
"Now, there's no call for such-"
"ENOUGH OF YOUR FOUL WORDS! WE'LL NOT STAY A MOMENT LONGER IN THIS FETID TOMB! LEAVE US NOW THAT WE MAY COLLECT OUR GOODS IN PEACE!"
"If... if that's what you wish, so be it." *leaving the room* "Urist?"
"Yes, sir?"
"Pull the lever."