I discovered another exploit tonight.
The king routinely seeks to extort gold from you, the penalty often being a "tea party".
All well and good; usually the player won't want to give that up. It's a good decision point especially if the king is seeking to raise the interest rate and it's already way high.
However, it seems the algorithm uses as criteria any good you've traded in Europe in the game so far. So, how about goods you don't really care about? Such as raw materials? Yes, ship 1 cotton, 1 lumber, 1 ore, 1 fur to Europe. The game will now dilute the "extortion" and the king will demand to raise the tax rate or you can no longer trade cotton. Whoo, I'll hate that.