well if we go into details like that, I guess you can say it's never 100% sure that Notty is mafia.
However, something really unlikely needs to have happend for the situation to make sense in another way, a situation where Notty is telling the truth.
What is more likely:
-Notty is lying and is actually scum. I did not visit Notty last night, and Foggy and Arelic are telling the truth about getting a report on Notty saying she is mafia.
Or,
-I visited someone else. Notty is 'tracker' and was visited by one or more players who firsly made her show up as mafia in investigations. In addition, Notty said she could choose a player and it would show her who he/she visited that night. She happend to choose me for some reason. Now, what came back to her was that I visited her. So someone has a role that can manipulate the information players get back from investigating. So then someone else visited her (or nobody), but someone manipulated the information so what came back was that I did visit her?!?!?
I am trying to make sense of that last one, but I just cant figure it out in my head, thats how little sense it makes. I know the second option might seem confusing, so dont be afraid to ask further on that one, maybe we can figure out another option to this sitiuation together. Or maybe Notty is just mafia, and we should lynch her.