Were you on something when you opted Trina Riffin for Complete Monster?
Srsly, your statement that "she never was redeemable or On & Off" is blatantly wrong. Remember her being nice to Mina in "Math of Kon" and the end of "Queen Bee"? Her love of Mr. Mooseface? Her literal repressed but still very much alive nice side in "Dreamreaver"? To top it all off, the show creators have confirmed she really cares for Mina and Corey deep down and probably will return to being nice once her angry teenage years are behind her.
Also, Trina didn't really cross any Moral Event Horizon with that monster truck incident since it was shown not to be deadly: the other racing team and Trina herself crashed (Trina's truck outright exploded!) and they were fine. It's a cartoony world, so real life physics don't apply.
I'm just confused, is all. How anyone can watch the show and think a typical comedic Jerkass like Trina could qualify for Complete Monster is beyond me.