That what tone is for! And when is written, you use the context. And when there is no context, you asume the kindest interpretation
So when a word that starts out as a neutral term to describe some condition or collection of people gets adopted over time by the general public as a slur or derogatory term, and that's how it is used 99.9% of the time, we should assume when we hear it out of context it is the 0.1% case?
Also for many of these words most the general public has complete forgotten the non-slur/non-derogatory meaning (or has never known it). No amount of tone will fix that.
Imagine an unmarried couple with a child who gets a copy of the child's medical records from their pediatrician and see the child described as a "retarded bastard". The chances that they will know that "retarded" was once a medical term for someone who is behind on mental development and that "bastard" means a person born out of wedlock are pretty low. At best they are going to be greatly puzzled by the doctor using those words.
It gets new mines because when a word becomes a widely used derogatory term for a group of people we need a non-derogatory word to use instead when when we are trying to talk about people in that group and aren't trying to be derogatory.