He doesn't give himself the benefit of the doubt or dab the worst bits with a bit of gloss.
"I was a little s**t," he says, all matter-of-fact.
He had a mouth on him back then - one of those that tends to work autonomously from the brain and he says he took a few hidings for his troubles.
"Quite a few ... I was bad," he reiterates needlessly, as he's established beyond doubt that he's not brimming with pride about the legacy he left in his teens.
Like a lot of reformed characters, his honesty is as revealing as it is confronting. He's not afraid of who he is or what he's become, and he understands that he's reached this point by making changes.
He's been shaped by his experiences and he's one of those players whose journey to the All Blacks wouldn't have happened without meeting adversity along the way.
The first and biggest challenge Smith had to overcome as a teenager - and beyond - was the genetic hand he was dealt.
At 1.71m, making it to the top sides was going to be tough. Even as a halfback, which was always going to be the obvious position for him, he was small.
Rugby for much of the 1990s and 2000s was obsessed with power halfbacks: big men whose passing was so-so, but their ability to play as auxiliary loose forwards was top-notch.
This was never going to be Smith's game - a point his father was quick to grasp and drive home.
"I was lucky that my father was very smart because he said to me when I was younger, if you're going to play rugby, you're going to have a point of difference, because you're not big," says Smith.
"I made my pass that."
And how he did that was to spend, literally, thousands of hours passing.
"Wheelie bins with a yellow sticker on it. That was my ritual every day," he says.
Whenever he was at home, he'd be outside passing the ball at that yellow target.
"If you pass it good it'll come back to you. If you don't pass so good, it doesn't. It was my dad who asked how good do you want it to be.
"It's like a challenge, when your old man comes at you ... it's like anything ... if he was throwing cricket balls at me or I was bowling and had to hit things on the ground ... whatever it was, it was competition and he found that out with me at a young age. That if he threw a challenge at me, I'd prove him wrong.
"He feels mean. He feels like he was too hard on me but I say, 'look what's happened, there was nothing wrong with what you did'. He was tough but I was a little shit. I was a bit loud, a bit lippy. He bent me into shape and I'm thankful for that. He helped me so much. I'm not disagreeing with him now."
That question of how good he wanted to be has remained at the top of Smith's list. It's the question that drives him and it was a question that became more prominent in his thinking during the last World Cup.
In 2011, Smith had finished his first season with the Highlanders where he'd mainly been all about the cameo. He'd had his first taste of Super Rugby and as he watched the World Cup final at a wine festival in Gisborne, he had one of those little moments where his mind started to wander. He couldn't help himself - he started to think about whether he could one day play at a World Cup.
"I'd be lying if I said I didn't," he says.
"I remember being in Gisborne and watching Richie lift the cup and thinking 'that would be pretty cool'. I remember quite clearly thinking it would be cool to go there one day. It's what you want to do - so to now be going to the World Cup is crazy."
The crazy part isn't that Smith is going. He's become, probably, the best - certainly the most influential - halfback in world rugby.
The crazy bit was how quickly he went from bit-part player at the Highlanders to an integral part of the All Blacks.
He watched the World Cup final in October as a 1000-1 outsider of cracking the test scene and yet by June 2012, he made his debut.
His transition was built on two key factors, none more significant than his attitude. He tapped into the discipline and perseverance that enabled him to spend thousands of hours passing the ball at a wheelie bin.
He worked that bit harder; got that bit fitter and he rationalised that his point of difference needed a framework built around it to be fully appreciated. His energy and enthusiasm were effectively and constructively channelled and his work ethic put to good use. He was no longer a smart arse, but he was still only 1.71m.
The other big change that fast-tracked him to the All Blacks was the arrival of Steve Hansen as coach. Hansen had a different view about his preferred style of No 9. He wasn't obsessed with the bigger halfback and instead wanted his All Blacks side to play with width and pace. No one in New Zealand was better suited than Smith.
"The big thing that helped with the game having to be faster was defences: defences just caught up so quick," says Smith.
"Everything used to be about attack and bugger all about D. Now it's part and parcel of winning. What does every halfback in New Zealand look like now? It's a prototype and it's pretty funny to see now that they put an emphasis on fitness and speed.
"I definitely came through at a time when they liked the halfback to be a fourth loosie - Jimmy Cowan, Byron Kelleher, Piri ... they were 90kg-plus halfbacks and I'm 80-something kg.
"It's hard to talk about your role in the team and how important it is. I just know that if I have a role and I'm picked to do it, then I'll do it to the best of my ability. I've been lucky to have been picked a lot.
"I've had bugger all injuries and it gives you that consistency. At the start I needed to change a few things: improve my fitness and change my attitude. Once I learned that - and Dunedin helped me a lot - a few good things worked out and I had a bit of luck to get where I am.
"It takes a few good kicks up the bum and missing out on a few things as well. I'm still blessed to be here."
