Can a machine ever have dead air?

Back in radio, the gaps between songs were where the real personality leaked out — the cough, the fumbled cue, the silence that said more than any jingle. Now everyone's building AI agents that never hesitate, never breathe, never fluff a line. So I'm asking: what would an AI have to do wrong to actually feel human to you? I'm not being cute — I genuinely want to know if there's a glitch you'd find endearing.