Since there has been some talk about it, a couple of ideas on
potentially problematic content in mafia games:
1.
Declaration on flavor content by the mod: In the signup thread. Something like
the PEGI system might be useful. Categories like violence, language, horror, sex, drugs or discrimination might be useful. Others might be added, like violence against women, violence against children, etcetera.
Example: in a Call of Cthulhu game, there might be a warning on
horror and
violence. The horror label might be there for suggestive descriptions. On the other hand, fully detailed descriptions of what happens to an infortunate human who meets a creature that really, really, should not exist, might raise the violence level to 12 or even 16. Finally, fully detailed scenes of torture of a defenseless being might grant the game a solid +18.
NSFW? Apparently, for most people anything goes but sex or matters related to sex. So a +18 game due to violence might often be considered SFW. (Agree, disagree?)
2.
Checking with the mod prior to the game: It can be done via private message or in the signup thread. A prospective player might ask the mod for clarifications on the content that might be included in the flavor, be it stated by the mod or related to something else.
Example 1: The mod M is to host a game where the players will be related to the mob in Las Vegas. M has warned that some violence might appear in the flavour text. Then P is thinking about joining the game , but this person, really really does not want to see much content related to
gambling. The mod might let P know what kind of content might be expected. For example, general references to casinos, game tables and the like (which might be OK). Or the contrary: the mod has ideas for setting some of the flavour during a protracted game of cards, where players leave the game as they get bankrupt, in correspondence with they leaving the game due to NK, lynch, etcetera.
Example 2: The mod M is offering a game featuring some well known superheroes and villains. Namely, Spiderman and Kraven the Hunter. The player P would love to participate, but suffers from arachnophobia. She checks with M if spiders are to be mentioned and how detailed might descriptions be (1). The mod might say that nothing beyond the name "Spiderman". Or, if that is the case, M might say also that the original idea was describing a scene where Kraven makes himself be covered with thousands of spiders, in an attempt to be impregnated by the essence of what means being
the Spiderman (2).
3.
Mods and players during the game: the semaphore: This is a simple but useful tool. When someone thinks that some text written by the mod or a player might be close to surpassing or has already surpassed what had been agreed upon with the mod declaration and the checkings with the mod prior to the game. It can be made via
PM TO THE MOD and PM FROM THE MOD. It uses a simple color code:
RED: This is more than what I expected to see in the game thread. (If it comes from the MOD: "Curb it or stop it").
AMBER: This is bordering my limit. (If it comes from the MOD: "Be careful where you take this").
GREEN: I like this. It is OK for me if you/the other player want to take it further. (If it comes from the MOD: "You have leeway to take this further if you want").
Example 1: In some flavour text for a game set in a hotel resembling that of The Shining, a boy of 12 is [REDACTED] by a madman with an axe. The mod is not avoiding gritty details about the peculiar noise the [REDACTED] makes when it falls on the floor, or how it rebounds, then rolls, and about the red geyser of [REDACTED] that emerges from severed [REDACTED] in the [REDACTED], etcetera, or how the [REDACTED] of what was the kid's [REDACTED] keep [REDACTED] for a few seconds after the [REDACTED]. Player P signs a RED code to the mod M, explaining how no warnings about this kind of content appeared on the signup thread. The mod M might agree and curb the content in future posts. Otherwise, he might point the player to the warning and reply something along the lines of "Shut up, you [REDACTED]! You are the next to [REDACTED]! MWAHAHAHWHAHWHAHAHAHAHA".
Example 2: Player P is writing some text suggesting [REDACTED] against [REDACTED], including some [REDACTED] implications. Player Q is not happy to read this and would not like things to go more graphical than that. So he signs an AMBER code (via PM) to the mod M. M may agree or not (there might be some conversation via PM). If the mod M concurs, an AMBER code (or even a RED one, if M thinks so) might be sent to the player P. If the mod M does not concur, nothing might be sent to P, and Q might be invited to discuss this further after the game, so that others might provide input and a general consensus might be achieved for future games (or not).
Example 3: The mod M is hosting a game set in the world of the movie Highlander (1986), featuring Christopher Lambert and Sean Connery. He warned about violence and decapitations galore appearing in the flavour text. However, during the game, the player P thinks that M is holding back on the gore. She might send the mod M a GREEN code with the text "I want to smell the blood, pal".
All these are tools commonly used on other kinds of social games. They help preventing unfortunate surprises. Both for avoiding material NSFW or for different reasons. Sometimes people just shut up and leave or complain loudly. Both might be unfortunate results. Knowing that there are proper channels and ways for clarification and discussion of such matters can make all the difference in some cases.
(1): The player remembers well the Straczynski time with Spiderman.
(2) This actually happened in a Marvel comic (years before Straczynski).
Carradice: The idea of a Lovecrattian/Call of Chtulhu game, with the players being members of a cult and the scum being... undercover heroes trying to bring the cult down. Of course, every lynch is a human sacrifice :3 
JoeSapphire: Can Carradice be added to the hosting list? Thanks, but way more experience is required with mafia before hosting, I guess :) It can become a complicated game, and I think it is best to see how mods handle a variety of situations first. 
