The New Zealand coach has come in for heavy criticism Down Under despite leading Australia to second in the inaugural Rugby Championship and No.2 in the world rankings.
Quade Cooper blasted the head coach last month and described the atmosphere in the Wallabies camp as "toxic".
Now Campese has joined the detractors and reckons Australia have gone backwards.
"It's been very disappointing in Australia - we have struggled," Campese told BBC Sport Wales
"Unfortunately we have a Kiwi coach, who we have struggled with and he doesn't understand the way we play.
"Before last year's World Cup he got rid of Matt Giteau, a 92-cap brilliant player, just because he didn't like him - it's funny how coaches do that.
"We struggled at the World Cup. We had two wingers who are great finishers but two centres who can't pass the ball - I don't know how that fits into a game plan."
The Lions jet to Australia to face the Wallabies next year but before that the southern hemisphere outfit take on some of the home nations.
They have already beat Wales five times in the past year but Campese insists the RBS 6 Nations champions will have no better chance to claim the Wallabies' scalp.
"If Wales can't beat us now there's something wrong. They've had five other chances, at the World Cup and four Tests since, and still struggled. If they can't beat us this time forget it.
"Wales have to play with the same intensity week in week out - that's how you win matches and get respect. To win respect you have to go out there and smash the opposition.
"When Wales play the All Blacks you really give it to them and play really well but then against other teams they don't play with the same enthusiasm and against the Wallabies they play nothing like that."