I have just read through this entire thread, and it seems to me that one particular thing is leading a lot of people astray: on several posts we specifically have referees discussing whether "foul and abusive" language should be tolerated. But keep in mind that there is absolutely NO mention in the Laws of any sanction at all for FOUL language. This was removed back in 1997 (I think) and replaced with "Offensive, Insulting and Abusive (OFFINABUS). This was done for a good reason: IFAB felt that many players used "swear words" in their daily speech, and that in essence the football pitch is their factory floor. It truly seems to me that any ref who slips into calling it "foul" and abusive is guilty of thinking in an old fashioned way here. This discussion should not be on whether **** (on any match report (I have always been told to use the exact words in full, and it seems weird to disguise the word here, when we all know what it is), on whether **** on its own is enough for a red. It would have seemed far more to the point to discuss whether the word is used offensively, to cause insult or as a term of abuse. It may be that some refs here are saying it is offensive TO THEM (even if not to the players) and that is enough. In Law, they are correct, but may be fighting an uphill battle in a changed world. And insisting on using the term "foul" language is merely perpetuating a semi-Victorian view of what football should be.
For my own opinion it does depend on tone of voice. A player saying "you ****ing lucky ****" to a TEAM-MATE could (maybe) be acceptable. Saying it to an OPPONENT or THE REFEREE is a very different matter. and "cheat" to a match official is bye-bye.