(sparked by this)
In the past, users with more than 500 rep could retag questions without the edits beig sent to the queues. Now, they can't.
Does this mean that we should reject retags in the queue as "too minor"?
No, proper retags are valid edits. Even if there are other things wrong with the post, too.
For example, someone who doesn't speak english very well might not be able to fix spelling/grammar mistakes properly but he might still have enough knowledge on the subject to cleanup tags.
A good way to handle such suggestions is to check if the tag change itself is sufficient:
No, I don't believe all tag edits are too minor. I don't like applying blanket statements to all situations. If you want to reject them all, then you might as well not allow low rep users to do retag-only edits.
I think that the reviewers should be evaluating the post and the proposed change and make a decision as to whether the edit fixes everything (and in the case of tag-only edits) the proposed tag is necessary.
That being said, rep-farming with simple retags seems to have gotten out of control for some users, and maybe the problem needs a different solution:
I've been bitten by this issue in the past... A user went on a re-tagging spree, which looked a lot like rep-farming to me as he/she hadn't bothered to fix any of the other issues with the posts, so I rejected them till I ran out of suggested edit reviews.
I brought it up in a question here on Meta and it seemed that the community opinion, at the time, was that as a reviewer I should have gone through and improved or accepted them on a case by case basis.
Personally I think this approach drops a lot of work on reviewers, that could have and probably should have been done by the editor.
Don't get me wrong re-tagging is important for the site, but we should have some mechanism in place to discourage spree editing.
It seems to me that the real issue that needs to be addressed is spree editing, not re-tagging, the issue is just more controversial when it comes to tags. When users search for common spelling errors to run through or go through and capitalize "i", no one seems to have a problem with rejecting them as rep-farmers, but when users exhibit the same behavior with tags its looked at in a different light.
If users are going to edit they should be editing the entire post not just a single issue.