Can confirm. My favorite book on linguistics has an entire section on AAVE that talks about this.

So some people are better at bad English than others? Also, in what kind of classes is this knowledge useful?

Well, it’s not “bad English,” it is a formalized dialect with clear structures and rules that distinguish it from Standard American English, which is itself just another dialect.

And as for your second question: Like it says in the post. Linguistics. The scientific study of the nature and structure of language. It’s a pretty big and important discipline.

And there are different dialects within AAVE. The way people talk in NOLA – even different parts of NOLA – is not the same way people talk in NYC, is not the same way people talk in Alabama.