If a double-duh is used like: a distant bark from afar.

Then it’s meant to really drive the point home.

A good point made badly. “Personally, bad English is such a turn off” would have made even less sense.

Personally, it could be worse for me.

Your example is good, as it emphasises the bark is a long way away, but for me, personally; the original just seems excessive.

Neither is required, the statement is subjective so without a qualifier it is implied to be one’s own thoughts. Adding either is just flare.

For me imo

No hace falta poner “A mí” antes de escribir “me gusta”.