My gameworld of Alsatia tends to be on the rather dark gritty side of the fence, and doesn't particularily shy away from any topics, these included. But like anything, it has to be part of the compaign that it's in.. Everytihng for a reason, everything with a consequence.
We certainly have foul language in the gameworld, but it's used for effect, and to help show differences in areas of the realm. Grensha, a city founded by, and maintained by temples to the many gods, generally has a far cleaner mouth, than that of Voushta, a city roughly equivalent to Las Vegas.. "You can get it, in Voushta", or so the saying goes.
But language is used as a factor, along with accents, names, and demeanor as a tool to help the players make the determination of where someone's from, often without the roll of a die.
It can also help to indicate relative class level. In Alsatia, as in much of the modern world, those who are of a higher statusare less likely to swear, than those who might be froma more humble background.
One thing I've always respected about StarWars games is their
Blast expression.. If I had the time and ambition, I'd add more Gameworld specific curses to the game, as they Certainly add flavor. We do have some now, but they tend to be more variations on Earthisms. "By Sarx!", one might utter in a moment in which the gods (figuratively)turn against him, and luck in running dry.
Sex- Sex is certainly an element that manifests within the game. As I said in my introduction, everything that occurs, occurs for a reason, and sex is no exception. I find it frustrating, for instance, if when reading a story, the author will go into great detail of a courtship, detail the distinct look and feel of the room in which they stay, the way she looked into his eyes, and then cheat the audiance with something to the effect of "And then they had sex."
It breaks from the feel of the story, and isn't fair.
Now, that said, I know what I can get away with, with certain players more, with others less.. My girlfriend is one of the players in said game, so she and the NPCs get more detail, but that happens away from the other players, for everybody's comfort.
But that said, Bad things happen. We've had a lingering demon whom one of the PCs accidentily freed. As unfortunate as that was, the demon has had a bit of an interest in her since that incident, and has been fought on a few occasions. But in a recent game, he needed her attention for a plot line, and so he found her, alone in the desert.
And he spoke nicely to her, as he held her down, and made himself comfortable inside of her. He's not a particularly nice character, and rape is certainly inside his range of normal behavior. The PCs did find evidance of him, thankfully off scene, cutting a hole into a (hopefully dead) little boy's stomach cavity in order to fullfill himself..
And we've had Loving sex, with PCs falling in love within the game, and kissing, holding, and eventually marrying characters.. PCs have been given the chance to do whatever they want, and we see both good and bad from it.
As I said, it's an element in the story. The game isn't
about that, but it's something that can come up, and it's not fair to avoid it. But it all depends on the situation.. Sex is never just there for the sake of having sex be there.
As for Drugs, again we certainly have them in our game. The PCs don't partake, for the most part, because the tend to hamper performance, or at least make you care little enough

But one of our most beloved (well.. At least one of MY most beloved) NPCs is a herbalist named Alexander, with whom the PCs often speak when they need a certain something extra.
Because of the way the gameworld is set up, In the towns of the north, near Grensha (City of Many temples, remember), the distinction between medicine and "drugs" is made, where in many other places it isn't..
By Arling, a largish outgrowth of a city, made up primarily of Farmers who continued to migrate and move there in a vain attempt to make some money after recent food-price crashes, we see little distinction at all.
Corn is a Food, Beer is a Food, Black weed is a food, Thyme is a food, khaf leaf (some one else's post, but cool!) would be a food. There is no arbitrary distinction between "This is a Good plant, this is a wicked sinful plant"
In Nagog, a city which has far more of an evolved ritualistic government structure, we have seen the use of several herbs, which tend to be prepared in a very standard way, as they have for thousands of years. Tying perhaps into sex, as above, they have certain herbs that they sometimes wash a woman with, or give her to wash with, that would cause her body to tingle, almost like hydrogen peroxide on Earth, to try to make her feel nice...
Violence- We certainly have violence in the gameworld, but not as much as I'd like, as a limitation of myself as a GM. We have a lto of violence that occurs outside of direct combat, such as a major villian of a fireign army being killed, and allowing himself to be torn to pieces, for the good of his army and people.. (Long story
Torture cerainly exists, both physical and mental.. We've had entire game solo sessions focused on the torture of a player's character, involving locking him in a cell, and breaking his spirit, forcing him to do the bidding of a evil master in order to get a scrap of food this week, or to avoid being sliced by a wire..
We've had characters locked in 6x6x6 cells, with nothing to eat but the cockroaches they can catch scurring to feast on neayby corpses, and nothing to drink but the condensation of water against the bars...
We certainly have a bloody, and violent workd, but I certainly need to work on in-game-combat violence. To often in combat, I'll give a generic enough description, such as "Character A will swing her sword aroung again, finally with enough momentum to get past his damage resistance, and cut into him.", Rather than a longer, description of swinging the sword, cutting into him faster than even his wounds can close themselves, his flesh sealing around your blade, his black blood running down the length of the sword, and starting to run against your hands..
I find that I tend to get too distracted by the combat rules, for one, and for another, players get anxious, and want to get on with the fight.
It's childish, perhaps, and I hope we get better...
In free-form games, I'll often spend an hour describing and playing out a single combat, detailing each blow, each action, and letting players react in the same way.. That's a lot more fun, but takes a lot longer, works well only with certain types of players..
In all though, we use whichever elements of the world make sense in the story, and work to try to create a more engaging, involved gameworld, that the players can feel immersed in. It would seem horribly unfair to avoid any of those, or any other, subjects, as they occur in real life..
But we aim more for an interactive story, somewhat directed to fit D20 Fantasy rules.
Interesting thread, and Good question!
Colin "Isn't a game but a relfection of reality" Davis
Edit- Added more about violence and torture, as it was pointed out I missed it.