The South Korea international opened his heart about the painful jibes he had to face following his move from PSV Eindhoven in 2005.
But he still had to endure question marks over his credentials to play a meaningful part in Sir Alex Ferguson's blossoming side, with claims that he was signed primarily for his merchandising potential in the lucrative Far East market.
Now after picking up his second Premier League title and playing a pivotal role in United's Champions League success, Park believes he has finally proved that he was signed purely for his footballing ability.
"When I came first I heard about that," the 27-year-old told the Manchester Evening News. "People said that I was here for merchandising, but I couldn't say anything because I am a football player and had to show my ability on the pitch.
"I kept showing that and now everybody knows I'm not here to sell T-shirts."
Park is not the only Asian player to face such ignorant jibes. Similar criticisms laid at Japanese superstar Hidetoshi Nakata when he started in Italy.
But the former Bolton play-maker soon won his critics round, going on to play for Italian giants Roma and establishing himself in Serie A. Park hopes the experiences of both him and Nakata will open the door to more Asian players making the move to Europe.
He said: "I had proved my ability at PSV Eindhoven, but still European people thought that Asian players aren't good enough to play in Europe.
"But I always wanted to face the challenge and prove that I can play here. I will keep showing that.
"The criticism hurt a bit, but not too much because I know that historically Asian players haven't done well in Europe. But I think we can show our ability and that Asian players can play better than some European players.
"Now everybody is seeing that Asian players can also play in Europe so I am satisfied with that."
Park recovered from a knee injury to play a big part in the second half of United's double-winning season last term.
He impressed in the FA Cup and Premier League victories over Arsenal, as well as both legs of the Champions League quarter-final and semi-final wins against Roma and Barcelona. Even still that wasn't enough to earn him a place on the bench for the Champions League final against Chelsea.
Park was perhaps the most unfortunate member of Ferguson's squad to miss out, with Darren Fletcher selected ahead of him.
It was particularly disappointing for Park who had already experienced painful semi-final defeats in both the World Cup and Champions League.
But he is adamant that he will continue to push for a regular starting place at United, and should they go on to successfully defend their European crown next season, he is determined not to miss out again.
"This club is strong and everybody has quality," he said. "Individual players have to show their ability all the time.
"I got the opportunity to play against AS Roma and Barcelona which was good for me and an opportunity to show my ability. I am not first choice for this team, but I will keep trying to show my strengths and maybe one day I can be."