Of late a huge number of suggested edits I review seem to come from people with a poor grasp of English attempting to improve the perceived poor English of others – example here. Questions often feature imperfect spelling, punctuation or grammar but read very clearly, while the edits introduce Chinese whispers by taking responsibility for the quality of language while distancing the OP's intent.
It often seems to me that this is users (maybe unconsciously) practicing their English in an inappropriate forum. I don't believe this necessitates a new variation of 'invalid edit', but I do feel that there should be measures to stop these people wasting their time. Should these simply be marked 'invalid edit' or is there a polite way to use the custom message to discourage users from using SO this way?