I've played a few games of Settlers of Catan with friends and seen some deals emerge in the trading that don't seem quite right to me. When do deals that extend beyond the current trade become unbalancing?
For example: Player A is planning to build a road that will block either Player B or Player C from longest road. So Player A sets up a bidding war between B and C to control this future behavior. B and C offer deals like:
Any time I have two of (favored resource) I will give one to you
I will never attack you with the robber
At what point do deals like these cause the balance of the game to shift too far where it's not fun or as good to play? Balance seems to be the key in all games, and I just want to make sure deals like these don't kill it for the rest of the players.