I feel compelled to hard shield Corbin for 1) being new and 2) having a nonstandard communication style. I recognize quite a few patterns that are consistent between posts which consistently get misread as disingenuous when they're just different.
To answer your question of how we're getting reads this early in the game,
@Corbin, quite a few of us have the benefit of knowing and playing with each other in the past, so we can use our knowledge of how the others play (our meta knowledge) to figure out if they're playing with or without an agenda.
Another way to figure this out without knowing the players involved is to look back in the thread at who was talking to and voting whom, and what the nature of the interactions were, especially for the players who are now dead. Mafia is a game of social deduction, and who is killed and when often reveals who the killer(s) are, if you can figure out why a player was killed.
Another way to solve is to look at people's reasoning. Are they stuck and unable to reevaluate? That's often a strong indicator that they're mafia because mafia often picks a target to get mislynched and attacks that person in the thread. More experienced mafia players are aware of this and try to mitigate this by indirectly attacking their target of choice. Some very experienced players can emulate a lack of knowledge of other players'alignments, so you have to deduce their alignment through other methods.
KoD's playstyle is to bury everyone with wordage regardless of alignment, so to solve him, you need to analyze his content.