Look at television ratings. "Intensely Suggestive Dialogue" is enough to warrant a TV 14. Check it out here, almost every guideline comes down to a judgment call.
http://www.tvguidelines.org/ratings.asp
Sometimes theere will be warnings about "mature dialogue". What does that even mean?
Hot coffee was nowhere near NC-17/X. I've seen plenty worse(better?) in the average R movie.
Edit:SeaRex, you've got it totally backwards. Schwarzenegger can slaughter scores in prime time, as long as there are no tits or "big boy language". Try watching the average mob or action movie before 8 to see the ridiculous lengths television goes to to stop Johnny from hearing "Mother****er". Well, maybe the mother****er shouldn't be watching The Godfather, Part II!