Sometimes I find my self reviewing papers with authors who are not very capable English writers. I am a non-native speaker myself, and I know how difficult it can be to proof-read a paper in English, in particular if you don't have access to any native English speaker. If the scientific content of the paper is otherwise good, I therefore try to do what I can to correct grammar, poorly constructed sentences, spelling mistakes etc.
It often results in very long referee reports, which take ages for me to type. I was wondering if it would be proper form to simply scan a version annotated by hand, and attach it to the referee report? If you received such a thing, would you be grateful for the time spent, or would you consider it lazy that I did not type in all the suggestions in a proper report?