There will be times it is useful to know if an answer has come from a native speaker or not. For instance I am English and could confidently give answers about the German language but if a German disagrees, he's probably going to be right.
Sometimes whether someone speaks British or American English could be significant too (especially as native English speakers often aren't aware of US-GB differences).
Is there a convention we could use to make this obvious rather than writing lengthy declarations on each answer? Is this desirable?
One thought is adding something like [de] or [en-gb] to answers, or to usernames.