From the sticky. Bolded the pertinant ruling...ie there is no problem with using outside games as a basis for scum hunting. Feel free to mention or post links.
"Mafia Specific Rules
Breaking rules, not posting, or certain other behavior may result in a modkill or replacement in individual games; rules regarding this should be (and generally are) included up front by the moderator. Some rules apply to most games, and should be assumed to hold unless the moderator explicitly says otherwise. These are:
Do not attempt to play the same game under more than one name.
Do not bring outside influences into the game - this includes threats, bribes, wagers, promises, alliances, etc.
Using knowledge from previous games is perfectly acceptable
, but try not to carry grudges from one game to another.
Do not talk outside the game thread about an ongoing game except where allowed to do so by your role. Likewise, do not use bbcode to hide secret messages - this equates to discussion outside the thread.
Do not edit/delete posts.
Do not quote communications with the moderator (in particular, your role PM). Paraphrasing is usually ok.
Do not talk after you are dead or replaced. Some moderators do allow contentless "Bah!" posts, but you should never reveal information once you are dead.
Play to win the game"