All of the following is IMO, so YMMV.
"Accent bigotry" - Irish = stupid & possibly a drunk; Northern Irish = bigoted & possibly a terrorist; RP English = educated & probably trustworthy (though also nowadays possibly a villain) - is one of the reasons I'm ... let's call it "ambivalent", about what TVTropes calls "Funetik Aksent".
"Phonetic" misspellings and dropping letters in favour of apostrophes happen at both ends of the literary social scale, but there's seldom any doubt about who's in "Who's Who" and who isn't.
The person who said this:
"Bless your ’eart, sir! I'll go up and tell 'Er Lydieship now, sir, and I bet you’ll be ’earing something in ’arf a jiffy."
didn't go to the same school as the person who said this:
"Dinin' at a London club, deah boy, then huntin' an' shootin' an' fishin' in th' countreh. Whatevah could be bettah?"
Further lot development may and should reveal that neither of those speakers are what they seem - salt-of-the-earth working class or disdainful peer-of-the-realm - but what they SEEM is telegraphed instantly by the way their speech is set in print.
(Sharon McCrumb did this in "Zombies of the Gene Pool" - a big burly man who sounds like a hillbilly villain from "Deliverance" is a linguistics professor born in the region and doing it deliberately to mock the assumptions of the people hearing him.)
Unless there's a good reason for it (for example, a character revealing their true origins by accident or for emphasis) often the only thing writing speech like that does, is to indicate These People Here Speak Properly whereas Theyum Fohx Theah Tawks Funnih.
That comes complete with baggage which the writer either doesn't know about, doesn't care about - or is fully aware of and using deliberately.
Other reasons for ambivalence: a little Funetik Aksent goes a long way; it's often tiresome to read (and to write); most of all, if readers are unaware of some important detail - such as what sounds the weird spelling is meant to imitate - it's pointless.
There's an example of Unaware right in the TVTropes article, which states:
Neil Gaiman's short story "Shoggoth's Old Peculiar" in "Smoke and Mirrors" parodies the New England accent found in Lovecraft stories.
For one thing, just looking at them would have shown that speech from Lovecraft stories (here "The Dunwich Horror")...
“They know it’s a-goin’ aout, an’ dun’t calc’late to miss it. Yew’ll know, boys, arter I’m gone, whether they git me er not. Ef they dew, they’ll keep up a-singin’ an’ laffin’ till break o’ day. Ef they dun’t they’ll kinder quiet daown like. I expeck them an’ the souls they hunts fer hev some pretty tough tussles sometimes.”
...is nothing like speech from "Shoggoth's Old Peculiar"...
"And for me, too," said his friend. "I could murder a Shoggoth's. 'Ere, I bet that would make a good advertising slogan. 'I could murder a Shoggoth's.' I should write to them and suggest it. I bet they'd be very glad of me suggestin' it."
For another thing - this is much more excusable - that writer clearly didn't know about "The Dagenham Dialogues", a series of British comedy sketches from the 1960s. performed by Peter Cook and Dudley Moore.
(Not knowing isn't a surprise. Those sketches aren't as famous as they might be because of the infamous BBC policy of wiping / reusing programme tapes to save on costs and storage. "Monty Python's Flying Circus" almost went the same way; a lot of "Doctor Who" and many other popular shows DID.)
What's actually being parodied are the "Dialogues" characters "Pete and Dud", playing two acolytes of Cthulhu. They're described thus:
"Sitting in one corner were a couple of gentlemen wearing long grey raincoats and scarves ... sipping dark brown foam-topped beerish drinks..."
Rather, or indeed very, like this.
The Defence rests, m'Lud.
These acolytes discuss H.P. Lovecraft's style and vocabulary (overblown and eccentric), the location of sunken R'lyeh (just off the end of the pier, but handy for the shops), Great Cthulhu who lies dreaming (though temporarily deceased), and so on and so forth.
It's an excellent simulation of Pete and Dud and yet, apart from a couple of dropped-letter apostrophes, der's nun uv d'yoojul kunstruksh'n trikz. Instead it's done by matching the repetition, pace and rhythm of the originals.
Incidentally, "Shoggoth's Old Peculiar", the titular beer of the story, is itself a parody of Theakston's Old Peculier, a not half bad dark ale.
Note the difference in spelling: "PeculiAR" means strange or odd, "PeculiER" means a kind of Christian ecclesiastical court, so that's another beery association with a temporarily deceased god. Accidental, coincidental or deliberate?
And here are a couple of bits of "Dagenham Dialogues": One and Two.
