I've noticed it on two of my posts (1, 2), but I speculate this happens to other posts also. Relatively new users (with no edit rights), make tiny 2-3 word edits.
According to the faq:
Try to make the post substantively better when you edit, not just change a single character. Tiny, trivial edits are discouraged.
Technically, both the edits I linked to are not wrong, but the first one corrected my (okay, sometimes not-so-professional) grammar in two words, and the second one corrected my spelling, again, on three words. Both questions had a high number of votes and good, accepted answers (a month before the edits), so obviously the questions were clear and understandable.
I might understand if users with edit privileges were doing this, but making a 2-word edit still adds it to the edit queue, makes extra work for somebody who'll have to review it, and I don't see a (constructive) point in this.
When I feel a need to edit (like this post -- there was some info in the comments but not in the post), I first try to ask the OP to edit it in himself (avoiding the edit queue) and wait for a while (to see OP is making some actions on the site, or for some time to pass), and only then I edit the post. If there's some other mistakes I could correct (there were a bunch of lowercase "I"s in the question I mention), I do it while I'm at it, but if the post was understandable before, I wouldn't have edited just for that.
The only reason I could see for such edits is to claim partial ownership of the question. I hope this is not the reason but rather just experimenting with the site options, but still... Of course, I would not be participating in this site if I minded other people editing my question, but these honestly don't make much sense to me.
If, according to the faq, these kind of questions are really discouraged, how are we discouraging them? Should we try doing something about this, making these guidelines somehow more visible to users, or something similar? What's the community's view on this?
Edit Here's another one. Given, this is not a good question, but the edit did not really improve it - it just capitalized the title! Is this really considered a "substantial improvement"?