I'm glad it comes across that Haymitch is struggling. In the books he's hardly conscious half of the time. That's how much he drowns everything in alcohol because that's the only way for him to even get through the day. And by the time the games begin, Katniss is convinced that he will be no help to them at all. It's only the first gifts from outside that make her realise that he actually cares.

How is it in the book, do they have a conscience?
The book is from Katniss's perspective so you only learn what she knows. And she simply doesn't know. She only sees that the Mutts have the other tributes' eyes. She does bring it up, though, that they may have part of their minds as well. And that they may be programmed to hate her simply because she survived and they didn't.