How am I presenting Greece in poor conditions? I think it's very safe to say that if you're maintaining friends status with a CS, you screwed up pretty badly. The only possible exception I can think of is Siam with a Cultural early in the game, and even that's questionable now.
How am I unfairly skewing the math in Russia or Arabia's favor? It's pretty rare that I take back low numbers on a strategic or luxury trade from a hostile AI. It definitely happens if I have a lot of something, especially a specific luxury, but like any sane player I prioritize making high

sales over "bad" deals.
On Deity the AIs just don't run out of

. On lower difficulties they tend to start running dry around turn 80 or so, but it's usually still possible to get maximum dollar for luxuries and strategics from broke AIs if you're creative and use them to substitute for things like the

payment you'd have to make to balance an RA.