This is a good point and it baffles me to be honest. I said "great" manipulator because it seems to be working so far. Great manipulators don't necessarily need to be great with everyone all the time. Or maybe she intentionally wants us to think she's a poor manipulator so that we trust her more? But that surely fails Occam's razor.
To answer other comments, I didn't get this impression solely by watching her on TV, it is corroborated by her history as a politician and recently leaked emails.