I don't know if she's town or scum but she's this nasty to someone in every game she plays no matter what her alignment. When she does it to me, it gets pretty ugly. My opinion of her is pretty much in the gutter right now because there is just no reason for these attacks that have nothing to do with the game that she just keeps up with over and over like the Energizer Bunny. It's destructive, it's nasty and shows that she is incapable of playing without trying to destroy another person and the game in the process. She's a mean girl and she really needs a PL every time she does this and I say that knowing full well some may think I do too for my reaction to it.
I suppose the first part is true. Normally I would try to judge your not knowing someone's alignment as a town tell. but being as the scum are not in a PM together. It's kind of null. On the other hand your comments of self reflection give more of an idea that you want to figure out this game.
I don't know if I'm much one to talk on this subject. I've been in plenty of ingame arguments myself, but most of them revolve around
Me: "You said this"
Them: "Yea, but I meant this"
Me: "Well it's still scummy."
Them: "no it's not"
Me: "Yes it is" ~infinite loop.
Personal attacks walk a fine line in this game. You're scum! is obviously a personal attack, but it's related to the game.
GFY and you're a girl on her period are not.
Focus on deciding if a person is town or scum. Not on personality.