Craven de Kere wrote:
Thing is, the real corruption is from "could have" to "could've". It's a common if not pretty contraction.
ESL students frequently misunderstand it as "could of" but despite the sound no native speaker is really saying that.
Oh God, I've seen many native English speakers saying so -- "could of", even once I particularly asked an administrator of a big forum why he used "could of" when he posted his important thread in his front page -- he was a native English speaker. And those Americans, Brits, Aussies, Canadians etc. in his forum are used to the usage "could of". And who do you guess wrote the poem above? A native Brit, not me -- I cannot write that wonderful poem for the present at all.
But in my mind I accept the could have is normal which should be put in first place when writing.