Due to the international user base, small and big grammar mistakes are unavoidable on this SE. The top priority here is math, not grammar. And that's how it should be!
Despite that, I would actually appreciate any grammar corrections/edits of my posts. Since they would help me to improve my English writing. Maybe other users share this opinion.
Is it OK to ask for grammar corrections?
Is there a good way to indicate grammar corrections/edits are welcome?
For example, a short sentence at the end of a post could do the job (or less annoying, in the profile description).
But I see many drawbacks, for example asking for grammar corrections cases a shift of focus and effort away from the mathematics. And it is selfish, since the corrections are only relevant for the writer of a post and the benefits for the community are minor.