Poor speech is subjective. Usually said about those they consider less educated than themselves.
As I told my young daughter as we ate our meal at a McDonalds in the middle of Georgia a few decades ago...
(We are Hoosiers; with our own distinct dialect and pronunciation and sentence structure)
She said, as we began to eat, about the folks that took our order, “Dad; they sure talk funny down here.”
I replied, “No; WE are the one’s who talk funny down here.”
re: “(We are Hoosiers; with our own distinct dialect and pronunciation and sentence structure)”
Like “Warshington” instead of “Washington” ... I’ve noticed before (while in the Ft Wayne area).
No, it’s not subjective and it’s not about being superior. I was COMPLETELY baffled by my husband’s speech at times early on - had no idea what he was talking about (”let” vs “leave” with the dog outside....picture that). Rules and structure are important IF WE ARE TO COMMUNICATE. Otherwise it’s the Tower of Babel, might as well be truly different language.
One will NEVER learn that “structure” in proper English class or the handbooks used. Doesn’t matter where the class is or from where the teacher hails.
Even my husband knows it’s not proper, so does not WRITE it. He speaks it, but it takes a special stubborn ignorance to make the effort to write/type it!
Dollars to donuts you won’t hesitate to criticize “ebonics”, common black speech patterns. This is the same thing - bad grammar (NOT pronunciation/accent - that’s much different).