You're arguing in a circle. "The reason why he shouldn't be trusted here is because he's done things in bad faith in the past" "What has he done in bad faith

You're arguing in a circle. "The reason why he shouldn't be trusted here is because he's done things in bad faith in the past" "What has he done in bad faith in the past" Your assertion "He's doing so in bad faith right there". You can't also attempt to conclude your antecedent from your consequent.