Why does Mark Rubio always sound like the allegations he is making are not believable, even to him?

I swear, to me he sounds like it is all prepared facts that he looked up but never read them so he has no clue what he is saying and he knows it?

Everything is gathered and uttered for political punch but no actual conviction as he may know it is bullshit, but he has to say it anyway.

Anyone else get that vibe from him?