Australia coach Justin Langer accepts the national team's public espousal of high behaviour standards left them open to a heavy round of criticism following an unedifying final day of the Sydney Test, and found parallels between Steven Smith's crease scratching episode and his own "bail tapping" incident in Si Lanka in 2004.

While Langer went on the attack about some of the more outlandish criticisms of Smith in particular, revealing on morning radio that he had personally called Darren Gough and Michael Vaughan about their commentary on the episode, he was also self-aware enough to know that the way the Australia side has tried to make high profile improvements to team behaviour and culture since the 2018 Newlands scandal left many observers sweating on the next lapse.

When it arrived in the form of the captain Tim Paine's combination of harangues at R Ashwin and dropped catches during India's unlikely escape with a draw at the SCG, the howls of derision from around the world, particularly in England at the outset of an Ashes year, did not unduly surprise or alarm Langer.

"Just a good reminder isn't it ... I remember a great mate of mine told me a few years ago if you're going to build a house or a hotel, it takes years to do it, but it takes a couple of hours to rip it all down with a bulldozer," Langer said. "So we've got to be on top of our game all the time, but also our players are human.

"In a lot of senses they're in very different circumstances with how they're living, they have been through England, they've been through IPL, they've been in hubs, all that sort of stuff. But that's okay, we've just got to make sure we're on top of our game all the time.

"That's one of the challenges of leadership, that's one of the challenges of putting yourself out there and talking about culture and how important culture is. You can't slip, and if you do slip, you get criticised for it, and that's all okay. But we've hopefully had the courage to say 'no, no, this is what we expect, this how we're going to behave', so when we don't do it to the standard we expect, we expect to get criticised for it."

Early in his coaching career, Langer was profiled by the Good Weekend magazine and asked whether the episode in which he was cautioned by the match referee for inadvertently flicking off a bail during a Test match in Sri Lanka in 2004 - the over before the Australians appealed for hit wicket against Hashan Tillakaratne after Ricky Ponting noticed it on the ground - meant his integrity should be questioned.

Langer has always maintained the incident was the accidental extension of a habit of touching the bails as he walked past them between overs, and said that afterwards he was far more conscious of himself and did not do it again. Similarly, he expected Smith to be much more aware of the crease area being the domain of the batting side when he was fielding, even if no-one is calling for his many shadow-batting quirks to end.

"I actually spoke to Steve about it the other day," Langer said. "I reckon I tapped the bail every single time since I was 10 years old. I remember being interviewed a couple of years ago and someone brought it up then about whether I was the right person to lead Australia because of what I did in Sri Lanka all those years ago. I nearly fell off my seat. It was the most innocent thing.

"With Stevey he probably does it every single game or he does it regularly, and that's the joy of social media I suppose, and people out there making a living from having to make comments as commentators. But I am absolutely 100% that there was zero in [what Smith did], but it did remind me a bit of that. I'm sure Smithy will be very conscious of it now…as I was after that. I probably never touched the top of the bail again."

During a Zoom call on which Smith's manager Warren Craig was present, Langer termed some of the reaction to Smith as "ludicrous" and lauded how the batsman has carried himself since returning to the team.

"I literally cannot believe some of the rubbish I read," he said. "Anyone who suggests for one millisecond he was trying to do something untoward, they're way out of line, absolutely out of line. That wicket was that flat and it was like concrete. You need 15-inch spikes to make an indent on the crease and he went nowhere near the crease.

"So seriously, seriously, I thought that was absolutely ludicrous. In the last couple of years since he's been back, he's been exemplary on and off the field. He's let his bat do the talking, he was abused like I've never seen anything through England and he just kept smiling and letting his bat do the talking. Give me a break."

Paine, who fronted another press conference on Tuesday where he apologised for how he went about things on the final day in Sydney, was also squarely defended by Langer.

"Do I have faith in Tim Paine? You have no idea how much faith I've got in Tim Paine," he said. "He didn't have his best day, no doubt about that, but after three years he has hardly put a hair out of place, he's been outstanding as the Australian captain in everything he does, and he had a frustrating day."

Paine's public contrition had been the outcome of plentiful conversations between him, Langer and fellow assistant coaches Andrew McDonald and Matthew Mott following the end of the SCG Test, something the senior coach reckoned to be a healthy sign of how the team now functioned.

"If behind closed doors our guys are stepping out of line we talk about it, we've talked a lot about what happened on that last day and we'll continue to do that," he said. "I hope over the last three years we've shown ourselves to be really good people and sportspeople on and off the cricket field. We don't shy away - the captain got up publicly and put his leadership on the line yesterday and said 'that's not how we do it' and that takes great courage to do that."