Oh, I didn’t use to live in a very diverse area either so I get your questions. These articles cover the most recent literature on those accents though.
https://en.wikipedia.org/wiki/African-American_Vernacular_English
https://en.wikipedia.org/wiki/Gay_male_speech
There’s a book, How You Say It- Why You Talk the Way You Do—and What It Says About You, that’s really good if you wanna learn even more!

I’m familiar with the demeaning stereotype, ridiculously exaggerating the speech of poorly-educated Southerners; I’m old enough to remember Amos and Andy on radio. However, I’ve never encountered anyone — of any race — who actually spoke that way.

They were speaking English with a Welsh accent. I did know that for certain.

Watch a rerun of any TV show from the 70s or 80s with black characters. That’s the stereotype.

What’s “ghetto sounding”? I’ll admit that, growing up in Detroit, I did notice that a lot of Black people spoke differently than white Detroiters. However, then I moved to Texas and realized that what I thought of as Black speech was just the Southern accent common to Southerners of all races. Most African-Americans are descendants of enslaved individuals, who by and large, lived in the American South.

Were they speaking English with a Welsh accent, or were they speaking Welsh?

Are you certain you could tell the difference?

Are *they* certain they can tell the diffence?

The “Black accent” is the inner city ghetto sounding speech pattern sometimes referred to as “ebonics.” It’s not inherently connected to skin color, and certainly not universal even in inner city ghettos, but it’s the stereotype, as accurate (or not) as any stereotype.

“Gay accent” is more about mannerisms, as a rule, and tone of voice. We’ve all seen the stereotype on TV of the flamboyantly effeminate gay man or the butch lesbian. Even less accurate than most stereotypes, perpetuated by Hollywood, but the stereotype is associated with homosexuality, and not hiring someone for it could easily be viewed as illegal discrimination.

A glance at the Twitter account suggests…uh, Holocaust education and labor issues? Uh, oh…no?