I can't help myself. I edit everything. I can't even read the back of a cereal box without noting the grammar and punctuation.
The grad students I coach know that whatever they submit for my review will come back with many comments in the margins. Some comments are admittedly picky, and I've learned to label them as such, and to be tactful. They are really only suggestions, after all. Even student authors retain the right to accept or reject my ideas about what they should change to make their paper clearer, more specific, or more correct.
It's a pleasant dialog, for the most part. The good students like seeing their papers improve, even if the process is a tad painful. The great students embrace the process wholeheartedly, even the pain.
A few years back I coached a student who sent me his papers with comments like, "Be brutal. I can take it." It became a running joke between us.
I told that story to one of this year's students and he clearly took it to heart. The most recent paper he sent for my review was accompanied by an e-mail that said, "Be your usual ruthless self."
Requests like that make the Red Pencil Queen smile.