Only Jay/Styx will be unaffected, because she really has nothing much else to say, considering she's pretty honest. And a very average person still >.<
But the affected ones will be:
Archer/Serpent: Who might have a mini breakdown because she keeps saying the truth what the fffff-!?!? Lori/'Dite: She's going to reveal herself, and kinda beg for people not to hate her. Chances are she'll lock in her room for a while :| Anya/Morrigan: Okay chances are she will start rating the staff at MNU, and she's not basing her ratings on knowledge. Might extend to the 21+ crew >.> Lena/Sekhmet: Chances are people won't notice it because where did she even care about lying!? Some interesting opinions might appear though.
Also, if Polyxena gets in while the event is going on she won't be affected. But my reserve will. Because I'm evil.