I’d enjoy knowing who supports use of the word “ain’t” and who doesn’t.
I would never “ain’t” in formal speech or formal writing.
Casually, OTOH, I like using “ain’t.” I guess the pleasure derives from it being grammatically taboo.
It ain’t proper to use ‘ain’t,’ so I ain’t gonna stop using it. 
As we used to say when we were sprogs, “Ain’t ain’t a word; my teacher said it ain’t!” (Only, of course, it is a word, just a non-standard construction…oh, well.)
In formal writing/speaking, certainly not, but I’m not opposed to it in casual speech, although I don’t use it meself. But in the same general vein as “ain’t”, I’m told that I used to say “amn’t” when I was small…certainly more logical than “aren’t” when speaking in the first person.
Do I not? : Don’t I? :: Am I not? : Aren’t I?
I ain’t got no problem with sayin’ ain’t.
I think it sounds good coming from some people, from others, it just sounds horrible. I was raised in a rural Southern town and some of those people can get some use out of the word and do it well.
My advice is that if you weren’t raised using it and you have a college degree then don’t even try. It sounds ignorant, tacky, and contrived coming from someone that does it less than fluidly.
A drill sergeant or a truck driver may sound tough and authoritative using “ain’t” but a white boy from the 'burbs ain’t never gonna pull it off.
I don’t use it. I doubt I would use it. But I wouldn’t criticize someone for using it.
I mangle the language too well now to use ain’t. It is bad enough that I curse too often.
This is a bad habit from my Navy days when every other word was an F-bomb. I try hard not to curse.
Jim
I never use it, formally or informally. I think it sounds really “dumb hick”. It’s easier to say “I’m not” anyway.
I won’t say it formally, but I like it. I like saying words slightly off-grammar for fun’s sake. And I’m a born-and-bred Tennessean, so it’s indoctrinated in me.
I just cain’t help it (misspelling intentional). I would never use it in formal writing or speaking, but for Goddess sake I’m from the South! I cain’t help it!
I use it occasionally for emphasis when talking to employees. “If he thinks we’re going to pay for a plane ticket so he can come in just to get a steak dinner, he’s dead wrong. Ain’t happenin’.”
Never use it. Never plan to.
I only use it very rarely - as mentioned above, it is usually for emphasis. “Ain’t gonna happen, my friend” is probably about the only phrase I use it in. I’d never say something like “I ain’t going” or “She ain’t cool”.
Ain’t gon hurt nobody…
I caught myself today slipping into seriously East Anglian vernacular…it was something along the lines of “Tha’ ‘int gon’ appen”. Most of the time I’m fairly well-spoken (I think 
), and just occassionally I’ll drop into a different mode entirely. Oh, and my point - the presence of “ain’t” in local accents & dialects ain’t restricted to America.
I don’t use ain’t formally or informally. It makes me cringe when others use it, but I wouldn’t criticize someone else for doing it - I make plenty of mistakes in everyday speech.
My favorite use of the word “ain’t” comes from the old classic, "Is you is or is you ain’t my baby?
I don’t really see ‘ain’t’ as a mistake, though, just a dialect variation - though some so-called mistakes make a lot of sense too [split infinitives, anyone?].
Our version was always “Ain’t hain’t a word.” Or possibly, “Ain’t is a word, it’s in the American dictionary,” though I haven’t heard the latter expression in years.
As slang I don’t have a problem with it. Not for formal use though. I’m sure I used to say this on occassion, but it’s fallen out of my vocabulary (However, I’m fairly sure that I’ve never used the word hain’t, except as part of the above expression.) On the other hand, I once heard a fisherman wondering about this very topic, as he wanted to name his new boat “Hain’t mine.”
I’m a white guy from the suburbs of California, and I use it all the time. Especially in formal occasions. Sure, it’s contrived. That’s what makes it so much fun.