The contraction of “could not have” is “couldn’t have.” Not “couldn’t of”. Sorry for a short rant but fuck I hate this.
You and me both, buddy. Thing is, a lot of regional dialects pronounce it that way, so the typo will follow. Doesn’t nearly get up my gander up as much as “irregardless” does. 
But it’s important to note that it is often (usually?) contracted further in speech to “couldn’t’ve”. In some dialects, this is phonetically indistinguishable from “couldn’t of”.
Yes. What I was trying to say. Thank you! Still, it is grammatically incorrect. Or just use it in quotes when writing that dialect in a cool novel. 
Me too.
Drives me fucking crazy.
Yes, presumably the phonetic similarity leads to the mistake. It’s there without the negation, too - “could’ve” sounds like “could of”.
What I’m not sure of - because of the difference among dialects, do people mistakenly think the error (in speech) is more prevalent than it really is? Do people think other people are saying “could of”, when they are actually saying “could’ve”?
I actually wrote it that way but it felt weird even though I knew it was the right way to type it.
I’ll be honest and say I get that people type it because of the phonetic sound. Not really a Pit-worthy complaint but didn’t know where to put it.
However if you get me going on “amazing” it’s going to be a long day. 
Drives me crazy too. Almost as much as using “it’s” as a possessive.
True. But you spelled it right the first time. Double contractions may not be used in standard written English, but they’ve long been used in spoken English.
I think the fact people don’t see them written (since they don’t look at recorded dialect) may be why the “couldn’t of” spelling came about, and then extended to uses without the negative.
Personally, though, I say shouldn-nve. The T, which normally gets swallowed in shouldn’t, gets completely eliminated in the double contraction.
It doesn’t help that I’m actually seeing autocorrect change my “its” to “it’s”. It’s maddening.
“Could of” in speech does not bother me; what bugs me is those who write “of” instead of “have”. IIRC, there is a recent thread on this board with “of” instead of the correct “have” in the title.
The other things related to this that bug me are: using “I” instead of “me” as an object pronoun, using “myselr” instead of “me”, using apostrope s for a plural instead of just using the s, and of course, misusing “its” and “it’s”.
Makes me wince a bit, but it’s become so prevalent it’s likely never going to go away, and will soon enough become “correct”. There are several words (hundreds, maybe) we use now that were originally spelled and pronounced differently, but we distorted them so much that etymologically they lose their sense, but seem right to us now. “Could of” is very likely going that way too.
Sometimes I get annoyed at “alright” when it is more correct to say “all right” but considering we have always, although, also, already, etc, it really ought to be “alright” and it’s really just the last one to resist.
One I will never get past, though, is the misuse of possessive apostrophes after S words, when it’s supposed to be only after the plural S, not any word or name that ends with an S. It should be Chris’s, not Chris’. Argh!
“Could of”, and “should of”, etc. are unacceptable and should be forever. There’s no excuse for that illiteracy. I learned this in like grade 5.
The SAT/ACT people scour the internet looking for such errors-I’ve seen them tested, on both tests.
Agreed. Looks annoyingly illiterate to me, but we’re increasingly stuck with it.
As other said above, it’s less-literate people converting spoken/heard speech to text.
One thing the internet has done in spades is give every monkey a typewriter. One with enormous reach to the other monkeys. We are seeing the democratization of spelling and grammar before our very eyes. Those used to be the province of dictionary and textbook writers and teachers of all levels. Not anymore.
I believe you’re thinking of
Which is fingernails on a chalk board as the OP keeps repeating his novel spelling, run on sentences, shifting grammatical POVs, etc.
At least one dictionary out there has added “irregardless”. There are days when I hate descriptivist dictionaries.
My sloppy dialect makes it “couldn’t’a,” and actually the “t” is silent. Relax, I didn’t breed, it dies wid me.
We usually just call them “dictionaries”.
Every time I see that, I have a little internal debate with myself, usually coming to the conclusion that if the writer had received an adequate education, they wouldna made the mistake…