To make things even more confusing, if we take a look at the Wikipedia definition of guro:
Ero guro puts its focus on eroticism, sexual corruption and decadence ... The term itself is an example of wasei-eigo, a Japanese combination of English words or abbreviated words: ero from "ero(tic)", guro from "gro(tesque)", and nansensu from "nonsense". In actuality the "grotesqueness" implied in the term refers to things that are malformed, unnatural, or horrific.[1] Items that are pornographic and bloody are not necessarily ero guro, and ero guro is not necessarily pornographic or bloody. The term is often used incorrectly by western audiences to mean "gore"—depictions of horror, blood, and guts.
If we were to say that guro becomes a tag for Grotesque, Unnatural, Malformed, etc...
we could then split the definition of the violent, bloody and dismemberment part of guro into a new tag, let's say graphic_violence.
Guro would become a very subjective tag then, but people that are really put off by the blood and guts can then blacklist graphic_violence instead.
My guess is that the majority of people aren't necessarily put off by blood and guts, but they will be if it's presented in a violent and gruesome manner.
The majority of s_zenith_lee images comes to mind.
To show how it could work, some possible examples:
post #1519939; graphic_violence yes, guro no
post #1340639; graphic_violence no, guro yes
post #1598937; graphic_violence yes, guro no
post #1065370; graphic_violence no, guro yes
post #1012864; graphic_violence yes, guro no
post #1398232; graphic_violence no, guro yes
post #777779; graphic_violence yes, guro no
post #1457902; graphic_violence yes, guro yes
post #1172553; graphic_violence no, guro yes
I'm sure that there are more images on Danbooru that could have both tags. I just can't find any other examples so far.
Only downside, a decent part of images with the what tag can be considered guro (think ao_usagi), so some weeding through the tag might be needed.