Deception is 100% guaranteed to work if you know how to talk

[Don]

Saw this in a critique of One Piece way back, but I think it's true in general in most fictional stuff. If you're capable saying words like: "XYZ is going to betray you", it is guaranteed to work even if you have absolutely no proof of any kind. By the virtue of being able to speak, your plan has to work because nobody in the world of fiction always accept any unfounded accusation to their best friends/family/whatever. Unlike the real world, in the fictional world people never argue. If this is the fictional world and I told you that Nintendo betrayed your trust, you're supposed to believe it unconditionally and burn your copies of Mario and Zelda games because how can anyone who is capable of speech be wrong? Why bother frame someone with phony evidence and do all the risk and being caught when you can just say 'don't trust this guy' and it'll work anyway?