I’ve mentioned a subtle way of doing this on my site before:
I also find that I have a subtle differentiation using singular versus plural tags which I think I’m generally using to differentiate between the idea of “mine” versus “others”. Thus the (singular) tag for “commonplace book” should be a reference to my particular commonplace book versus the (plural) tag “commonplace books” which I use to reference either the generic idea or the specific commonplace books of others. Sadly I don’t think I apply this “rule” consistently either, but hope to do so in the future.
Now I’m wishing that I had a separate “labels” taxonomy on my site to distinguish between “mine” and “theirs”. In using the Post Kinds Plugin for WordPress, I’m passively collecting labels (though it’s called tags) others put on their content (which is currently hidden in my internal metadata) and that is separate from the metadata tags I place on it. Being able to separately search the two could be a powerful feature.