Again, the question is more about them than it is about you.

But to answer your question: by asking for them, or marking it in your profile or similar. For example, I now have you tagged as "grammar check me, daddy" so if I see it in the future I'll know you're down. But the fact that one person may appreciate them doing it does not mean they have an excuse to be rude (and obnoxiously anglocentric on an international forum) to everyone, just on the offchance they'll like it.