I think I should clarify on NCFOM, when Bell quit, it was a realization that he couldn't 'see' this degree of evil. In the beginning soliloquoy, he said "to see this evil, you would have to be a part of it, sell your soul." Now Chigurh was in the room, and maybe Bell even realized in his gut that he was in the room, but he couldn't see him, he couldn't put together the disparate elements of what he had before him, the air conditioning grate and the coin, the presence in the room, so he came to a crossroads, sell his soul and track this down, or wake up and retire.
You ever notice how on stop lights, green means go, but on a banana it's the opposite? Yellow means "go ahead." Green means "slow down." And red means "Where the **** did you get that banana?"