With Dany, I think it's a combination of the character being more placed in a position of power as well as her rocking her new blue pimp cloak of pimpness. Indeed, in Season 1, she was first sold off to and then dependent on Drogo. And in Season 2, her Khalisar was in ruins and she had to resort to begging to survive; whereupon she was played as a pawn. In contrast, Season 3 has her negotiating to buy herself an army and then taking out a whole city after tricking the slave masters.
Speaking of her little stunt... Much as when I first read the book, I can't help but feel that it was a stupid thing she did. Sure, she got to keep her dragons and gain a huge Unsullied army. However, it also sent the message to her potential allies that she is someone who is not to be trusted. She will not necessarily honour her end of a bargain and she will turn on your at a whim if she feels like it.