I think in Murder Machine that Montiglio embellishes his stories in that he is always twisting things to make himself look like a good guy or a victim. I don't think the stories he tells about other people are out right lies, just that he slants everything to make himself appear to be a better guy than he was.

He's always complaining about nino and while nino is not a nice person by any stretch, nino never really gets in dom's way and is rather lenient with him given that dominick doesn't act very responsibly at any point while living there. He acts like things are supposed to be handed to him (always complaining about how much nino pays him) and never really does anything on his own or when he does he blows it on coke and booze. Nino never tells him not to earn, just to stay way from the demeo's. Instead dominick didn't earn and did hang out with that crew