There is a metaprinciple for the entire Gentle Art of Verbal Self-Defense system which says that in verbal confrontations and disagreements your goal is that there should never be a loss of face on either side. That applies to every technique, and is intrinsic to the system.
When a response would mean sacrificing your dignity or compromising your principles, it’s not satisfactory, and something else should be chosen in its place. What that “something else” will be is going to depend on you, the person(s) you’re talking with, and the context; all I do is provide some tools to use in making your choice.
Does this apply to everyone in your life? I tend to get very snarky if someone attacks me verbally. Just how snarky depends on how important the relationship is to me. If I actually care about interacting with the person, I don’t need to “win.” If you focus on coming out ahead instead of improving and maintaining the relationship, you lose the relationship.
I will cut other people down without hesitation, though. I suppose that’s petty of me, but if someone attacks me for no particular reason, I figure they need to be cut down a bit.
And yes, random strangers do attack fat people, especially. I know there are others who have experienced these kinds of unprovoked attacks, too.
They don’t expect the target of their attacks to respond with anything but embarrassment. We’re fat people (or queer people, or dark-skinned people, or whatever). We’re supposed to roll over and take it, right? We’re minorities!
In my experience, the attackers usually make these attacks in our hearing, but not directly TO us. We aren’t supposed to acknowledge them. It’s part of the attacker’s assumed power.
Sometimes, they aren’t worth a response. Sometimes, though, if I happen to have the time and energy, I will take them down verbally. In fact, I enjoy it.
Are the attackers likely to learn anything from it? Honestly, no. But they aren’t usually open to much in the way of education anyway, and they aren’t my problem. If having an “easy target” respond in kind is enough to make them think twice before attacking others in the future, that’s enough for me.
The Gentle Art of Verbal Self-Defense system is great for communicating with people with whom you are in a relationship. Communication techniques are no more “one size fits all” than any other part of life.