So the tags "lily", "lillie", and "lilly" are currently quite a hot mess right now, with ambiguity and mistaggings up the wazoo.
The tag "lily" is currently a character tag, and is on 29 posts. However, there's a problem, because there are a fair variety of characters with this name. For example, a frog villager from Animal Crossing, a My Little Pony character, and a large variety of OCs. There is also the flora named "lily". This would ordinarily be a simple alias of lily → lily_(disambiguation), right? Well, there are two plant-related tags in use. There's lily_(plant), on a single post, and lily_(flower), on 52 posts. Not to mention that some uses of lily are referring to the flora and not a character named Lily. Therefore, there are solo posts with more than one character tag.
"Lillie" has a similar issue. It's less likely for a mistag due to the plant's correct spelling being "lily" but it could still happen. There's an imadeej OC and a Pokémon character with this name. Thankfully, the tag itself has only a single post, but it's still an ambiguous thing. (maybe the character owner could be appended to the end to fix this, and have "lillie" itself disambiguated?)
"Lilly" is also used as a name, but is commonly tagged for the flora and the Pokémon character by mistake. (One being "lily" and the other "Lillie".) It has been tagged 33 times. This one might not seem problematic but it can be. For example, if a person does not know the spelling of the Pokémon character's name and they don't want to see images of her, they might blacklist "lilly", which would hide innocent images of the flower or other characters of this name, and while a few mistags of Lillie would be hidden, it would allow a whole bunch more images (109 as of current) to slip through, as that is not the correct spelling of her name. Inversely, I have hidden Lillie images which aren't rated S, but searching "lilly" allows me to still see some, and potentially, the "lily" tag, too.
Updated by ImpidiDinkaDoo