I dont think the games AI views 'destroy' as taking over. Destroy would be to nuke or creating a park or infecting etc. As an example, I disliked the Irish, cause they were the only other power besides me, so I declared war on them and nuked Dublin (their capitol). Soon after i requested one of their other cities (Edinborough which they took over from someone else). And when they rejected, I threatened to destroy Blarney. They then succumbed and gave me Edinborough without any resistance (very nice i must say). Then i asked for another city (i forgot which) they rejected. I threatened again to destroy Blarney again, and they rejected, so i nuked Blarney (I am a man of my word
). I didnt go much farther into the game cause I changed around some files, and wanted to start a new game with the modifications. So I couldnt really continue 'experimenting' with the Ireland negotiations
But anyways, I guess next time when you threaten to destroy a city, and they dont listen, really destroy it, they may be a little more giving the next time around. Heh, playing with those fun toys though doesnt really win you high honors with other civs though. But if you are playing on bloodlust, who really cares right?