I've made tags for stuff I have on my hard drive, and I have separate tags for appearance and canon information. For example, an anime character who's 3404240856376893746082 years old, but looks like she's 8, could be tagged both with "loli" for her appearance, but "canon_adult" or something, to indicate that in the context of whatever series she's from, she's really not a kid. I think Danbooru could benefit from this in two ways:
1. People who happen to want to look for characters who look young but really aren't, could do so.
2. If these tags were widely used, it would be more likely that the average user who doesn't read the rules, forums, or the wiki, would be aware that tags like "loli" are meant for appearance, not actual storyline info/whatever.
This would also be used for tags like incest, milf, etc., not just loli. Some of the "ELITE" members of DB don't like the "incest" tag, for example, but people should be able to search for characters who are related, even if their being related isn't conveyed through the image alone. Same for characters who are mothers, but don't have the stereotypical "milf" look of curvyness/maturity.
maybe you will like this idea, maybe you won't. Just an idea.
Updated by Lalaca