I agree that sometimes the TOS seems to be waaaaaaay too  "open to interpretation" to put it kindly, but generally an artist knows what passes and what doesn't.   I remember posting what I thought might be a borderline pic a while back.  Trouble is I only thought about it after I posted it so I contacted the admins/mods offering to delete if it was deemed offensive.  It was deemed offensive, I deleted it...end of story, except to say the whole matter was handled in exactly the way it should have been; politely.
The fact that I didn't consider it offensive has nothing to do with it.  There are plenty of places to post my work and it was acceptable in the other places I chose to post it,  and no, I don't mean "adult" sites either.
 A  painter wouldn't walk intro a gallery and throw a hissy fit if they refused to exhibit his or her work, on whatever grounds.  Why do people assume online galleries should be any different?

The liver is evil - It must be punished.