Here is a long list of things that I have seen hosts and/or admins do that ruin the game:
#1: Hosting Mafia Madness on a map other than the default Pyramid.
/support
#2: Screwing with the environment.
/support
#3: Host and/or admins messing around outside of the minigame (or when they are dead).
/support
#4: Messing with the MM "locations".
/support
#5: Placing lights.
/support
#7: Host and/or admins messing around or spamming with eval.
/Support
#8 Hosting a dedicated MM server.
/support
#9 Host and/or admins not knowing the rules themselves.
/support
#10: Starting the round too quickly and not asking people to read the rules.
/support
#11:[/b] Setting the player limit too high.
/support
#12: Banning players without asking for their side of the story.
/support
#6: Make designated body piles.
Now the body piles like "cops" "admins" and other things are a nono
however, I like having a place too put all the dead.
If we have one body pile stuff like this can happen:
Pile of Bodies by TomTom's Server Artist TDcoolguy is an interpretive statue of dead bodies.
The 10+ tier tower was skillfully crafted by a jetless player during TomTom's Mafia Madness mini-game.
Unfortunately, however, TDcoolguy fell from the tower and died shortly after completeion, allowing the mafia too win the round.