Considering the extraordinary difficulty of keeping a meaningful number of human players in one spot for the length of the average civ game, we're lucky it's as good as it is.
But like most AIs, you notice exploitable or cautionary patterns. Nobody has ever rushed me with ridiculously out-teched units, but they've certainly declared inevitable war on me for the crime of being with 5 squares of "their" land, as my borders grew enough to touch their own.
And in Civ 4, well, do you have any religion at all? Congratulations, every other Civ with a different religion in the world will hate you in increasing factors over time. Better rush Free Religion or forgo all the early religion bonuses. And good news, the AI is wildly biased against being asked to change religion. Fortunately, not from doing so naturally if you missionary every single city they have.