Except that (I think!) Meg proved herself when she battled the hellhounds. She'll willfully make sacrifices and it isn't all about self-preservation. That pings with the Winchesters more than Crowley's special brand of "Come on, boys! You can trust me ... *wink*" Crowley is deceptive in nearly every transaction he makes. Meg had a sense of mission and scruples. For a demon? That's saying a LOT. I just don't think that comparison is parallel.

Crowley and the Winchesters worked together in that they needed each other. I don't think there was ever a doubt for either of them that as soon as their usefulness to each other was done, all bets were off. And frankly, if Sam had been softer to him, it would've made Sam look like a dupe when Crowley made off with the First Sword at the end. So I'm glad he didn't get all touchy-feelie with the guy. Makes if funnier too! ;) (All that being said, I adore Crowley. He's the scoundrel you just love to hate!)