The AI does the same thing to me (or tries to), except usually w/ Research Agreements.
This and the related experienced human can just look at the map and know the AI is about to DOW them in one or two turns (and consequently buy out the AIs entire treasury) both expose that the military adviser part of the AI does not talk at all to the foreign minister adviser.
RA issue : This is a lot less of a problem in G&K: First because you now need a DOF for this, and second its worth a whole lot less so there's less incentive to sign these with players anyway, especially with AIs an era behind [which is the case where the human lost more cash]
We also have issues with trying to bring back sanctions for broken trade deals (Civ III)
It wouldn't be quite as bad in Civ V since roads aren't needed, but you still have the issues of assigning blame. If we blame the person who did the DOW, then the human signs a deal for cash now on his turn knowing that not only will we not have to pay for it, the other AIs will also blame that AI for a broken trade deal. And if we blame both sides, then the human is going to become nervous about signing even straight luxury for a luxury deals given the length is 30 turns.
Much easier to avoid these problems by just bringing back Civ IV's rule and have humans adapt to getting 7 GPT* from selling a luxury instead of in 240 gold cash dumps.
*The 7GPT is assuming they don't get around to fixing the bug that the AI is willing to pay more cash now than in GPT for a luxury.
But it turned out the main reasons the AI has cash now to begin with are:
1. Until a recent patch, AI would only cash rush units if it thought it was behind. (Now it will also cash buy if it thinks its even)
2. AI does not know how to cash rush buildings at all. This is also the main reason the AI needs the massive happiness bonus [humans cash rush them in slow production cities when needed] and its also majorly slows down expansion AIs at building national wonders.