How do you find scum when playing mafia?
Well, if you were to play this game in person, you'd probably look closely at the people around you, see if any of them looked like they were hiding something. Subtle changes of expression and social clues can give someone away when they know something they don't want anyone else to know. Of course, that's hard to do online.
Hard, but not impossible. People still have a certain tone to their posts - frustrated, playful, bored, so on. People still have hidden agendas - flying below the radar, getting a player who suspects them out of the game, making other players trust them, and so on. People might not seem like they think anyone is actually scum. These are clues.
If you're still not sure what kind of behaviour would suggest someone is mafia, I can give you a place to start. A much bigger mafia forum has its own wiki, which is often used as an unofficial resource on Bay12 for things like role names, mechanics, etc. It's called
https://wiki.mafiascum.netThere are certain indicators that someone is scum - you can look for these in the way they post. Have a look at the pages here:
https://wiki.mafiascum.net/index.php?title=Category:Common_TellsI'd especially have a look at the tells here:
https://wiki.mafiascum.net/index.php?title=Mini%27s_Scumhunting_Kitand even
https://wiki.mafiascum.net/index.php?title=Mastin%27s_Insane_Tells for some more out-there theorising.
Not all of these are accurate or even likely to be useful, but it might get you thinking.
And once you've picked up on something odd someone's doing, or maybe one of the tells above? Ask them about it. Push them. Make them explain why they did it, what they were thinking. And see if you buy their explanation.
(and the great thing about this game is that if you don't, you can shoot them)