The simple truth of the matter is that a constant barrage of vulgarity will only limit your options. If the language in your film warrants a hard-R or an NC-17 rating, your chances of profitability will fall dramatically. You will never get any over-the-air broadcast, or even any basic cable if every other word in your film is f**k. Sure, the premium channels will run films like that, but, unless you have a major distributor backing you, you're not going to be on HBO anyway! Additionally, and more importantly, although WalMart will carry the major studio releases regardless of the language, trust me, they will not carry your little independent film if it is filled with vulgarity. I know what you're thinking: F**k WalMart. Well, just remember that 30% of the DVDs in this country are sold by WalMart. You may want to check with your investors first before you decide whether you need Walmart or not.
The first feature film I edited was called "Charm City." It was a slacker/college romp along the lines of "Clerks," and, true to the genre, it was exceedingly vulgar. The producers and director took it to LA. A few months later I heard back from them. They wanted to know if there was anything we could do about the language. It scared some distributors off. In fact, the film never found a distributor. This is not an isolated case. I am aware of other films limited or damaged by their vulgarity.
Yeah, but what about Kevin Smith? What about Martin Scorsese?
You're not Kevin Smith.
You're not Martin Scorsese.
Watch TCM (Turner Classic Movies.) The writers and directors of those films managed to convey the whole gamut of human emotions without the F-word.
It might behoove you to do the same.