Cullotta is a rat, end of story. Very small parts of Marino are based on him, but in reality he never was responsible for bringing the skim back to Chicago or anywhere else. He was Spilotro's lackey-boy, and flipped long before Tony was killed. He didn't even get to do any real damage to the outfit because Spilotro was the only one he had real interactions with, and when he died, there went any use for Cullotta. I think he may have testified at Joey Doves' trial, maybe a couple other small ones, but nothing huge. Now he parades around like some big badass who grew tired of Spilotro's antics. In reality, he was a junkie scumbag who complains about Tony doing the same things he did. He's not quite on the level of a henry hill type scumbag, but damn near.