I usually run a good fiscal policy, so my gold is always positive. I've read somewhere that if you get to 0 gold, units start to sell themselves. Are there any other repercussions?
What happens if you have a trade agreement with someone and you need to pay them X gold per turn, and you just don't have the money to give? Do they still get the money? If an AI civ runs out of money but still needs to pay you, do they still get the money?
I often see AI civs with 0 gold and a deficit, but they still seem to be able to field an army. How can that be? Is this behavior exclusive to AI civs?