It's been bothering my for a while now.
I use Google's Blogger for this blog and it has a handy "labeling" tool for entries which are then linked and displayed for easy access to various similarly labeled entries. It's a good function for the tagging practice that most people engage in.
But I'm different. I can't remember whether I started tagging when I first created the blog but eventually, I recognized the main problem with simple tagging. Most people use simple keywords to describe things -- politics, news, announcements, etc. -- and this is mostly fine. However, as your list of tags increases, ensuring that everything is tagged consistently and comprehensively becomes more and more difficult. At some point, you may accidentally start using a slightly different spelling at one point which will then start splitting your collection in two. Or you may start using a different word altogether. This may be a mistake or may even be intentional (e.g. using near synonymous tags like politics and government) seeing a difference in the entry that initially gets the new tag, but will also start splitting your content.
Also, as the list grows, appreciating the various types of tags becomes more difficult. We tend to use different categories of tags: subject descriptors and format types being the most common, but possibly describing audience preferences, included elements, or even subjective qualities. Again, with a short list, this is fine, but, as the list grows, your ability to mentally juggle all the concepts you had in your head when you starting using each term becomes strained. Did you use the "news" tag to describe news items you are posting, or commentaries on "The News"? Or was it a misspelling of "new" and this was for newly discovered tools? If you weren't vigilant enough in choosing your terms carefully (and I'm not sure any of us could be) then you will run across this problem eventually. My solution to this was to make tag type explicit, using extended tags such as "Subject: Ethics" or "Type: Commentary". Even then, sometimes I would forget what I meant exactly by a certain term and realize that two tags I've used should be merged.
However, given all that, I'm succumbing to standard tagging practice. I'm converting all my tags into simple terms and phrases, trying to make it obvious what I mean but not "extending" my tags to clarify tag category. My reason is mostly for space. Blogger gives only a limited number of characters in the label field so using extra characters necessarily limits the number of tags I can use. I'd rather have higher tag resolution (more tags per entry) than clearer tags. This space-saving measure also helps in the tag cloud displayed in the side bar, and makes the list of tags in each entry a little more readable.
Finally, the purpose of this entry was not primarily to describe my retagging project, but to explain the existence of the "(checked)" tag. This refers to entries I've looked at and am now happy with in the context of this effort. When I'm done, I'll delete them all.