Been lurking MFC for three years and on there for a year. So far my experience is MFC picks and chooses who gets in trouble. Sometimes you're the unlucky one who gets a warning for whatever unacceptable behavior is listed in their TOS.
There's a lot of written down "no, no's" that MFC lets slide. Fisting, mensturation, urination, men on camera. The only ones I've seen enforced are sexual acts with men on camera and children, of any sort, on camera... if they're reported. And under aged girls, again, if they're found out.
Other than that, MFC seems to be an "anything goes" brawl for who can be the dirtiest girl with the highest cam score.