Farmer Exploitation, as told by WoW.

Using WoW machinanima to illustrate the practices of exploitation in the real world:

Here's the explanation of the video for you non-WoW players.

A troll farmer gets a return of 90 copper pieces for the sale of 20 pieces of Runecloth.

The Runecloth is sold at the Silvermoon Auction House for 2 Gold and 20 Silver (the equivalent of 22,000 copper pieces). A caravan brings it over for 10 silver (1000 cp), after being sold to an orc corporation for 80 silver (8000 cp). Presumably, the orc corporation takes the 13,000 cp profit, and then sends out from that 90 cp to the famer.