Gut
From SA Mafia Wiki
Gut, or a gut case, is when a player suspects another is Scum but just cannot put into words why they feel this way. Because gut cases are emotional and are not based firmly in a player's actual behavior or postings, they are not considered "real" cases. Gut cases are common early in Day 1, when there isn't much to go on but hunches and suspicions, but lategame voting for a gut case is considered a big cop out.
In general, gut is a good way to know where to start making cases, but in order to avoid confirmation bias remember that it's only gut, and nobody's gut is perfect.