Quite often, I see something like:
Sorry if the language is not perfect, I translated the quotes from german.
Sorry, English is not my native language.
in questions (and, although more rare, in answers).
Although I'm far from writing English perfectly, I think most people are able to understand what I write. So when I see such a notice, I try to fix the language as well as possible. Should I remove "bad English excuse" notices after improving the language?
I would say that such a notice can be removed as soon as the language seems to be good enough to be understood. In my opinion, there should not be any "sorry" or "thanks in advance" or, more general, be anything that is not part of the question. If people see minor mistakes, they can edit the mistake.
According to Should 'Hi', 'thanks,' taglines, and salutations be removed from posts?, many people seem to think that is a good idea to remove "Thanks". So I guess almost the same reasons why people think that salutations should be removed apply to removing "My English is bad" excuses. But I'm not sure about it, so I would like to hear your opinion.