I'm a lifer, yeah... I can honestly say I'm a lifer.
'Dirtbag' is just the term we use, like a 'gnarly dude' in surfing.
Within the climbing culture, it means being a committed lifer: someone who has embraced a minimalist ethic in order to rock climb. It basically means you're a homeless person by choice.
'Kitchen Confidential' wasn't a cautionary or an expose.
I wrote it as an entertainment for New York tri-state area line cooks and restaurant lifers, basically; I had no expectation that it would move as far west as Philadelphia.