A while ago I earned the Copy Editor badge after spending a pretty serious chunk of time editing posts on Stack Overflow for grammar, content, formatting, etc. I still do this from time to time, but I have a lot less motivation to do so since from here on out I know that I'm not going to be earning any more badges from it. I don't want to seem like I'm "badge-grubbing," but badges do act as a strong motivator.
Would it be possible to create some sort of badge that can be earned multiple times for making edits? For example, there could be a badge for "edited 100 posts" that can be earned multiple times, so that every 100 edits you make you get another badge to your name. That way, you always have some sort of incentive to keep improving user posts and making the site cleaner and clearer.