I honestly can't understand why so many people are mad at Ben for Carley/Doug's death. IMO, the fault for that is 100% on Lilly. Okay, it was Ben's deal with the bandits that set things in motion leading to that point. But there's no way he could have predicted Lilly becoming so completely unhinged and murdering someone in the group for absolutely no good reason. He didn't force that psycho to pull the trigger. In fact, he was trying to talk her down.
And really, Ben's deal with the bandits was probably the only thing that kept them from attacking the motel sooner than they did. The only thing I can really fault him for is not coming to the group and telling them about it when he first made the deal. But even that's pretty understandable if you think about it from his perspective. Lilly wanted to toss him back out to the walkers from the start. Kenny was against bringing him back to the motel, and he openly insults Ben's ability to contribute. We'd already seen that Kenny's willing to kill people in the group if there's even a slight possibility that they pose a threat. Even when Lee and Carley talk about him, you can tell from the way they talk that they don't think much of him. With folks as welcoming as them, why would Ben trust them? Treat a guy like an outsider long enough, and eventually, that's how he's going to start seeing himself.
Personally, I still trust Ben more than I trust Kenny. Especially after the way that Kenny didn't even lift a finger to help Lee while he was being attacked by a pile of walkers at the beginning of Episode 3. At least with Ben, even when he screwed up, he was still genuinely trying to help.