The Irish were fuming after officials failed to spot that Rees had taken an unlawful quick line-out - he had used a different ball that had also been handed to him by a ball boy - from which scrum-half Mike Phillips scored the crucial try.
Rees has stated that he would not hesitate to take the same action again and Best - his opposite number in the championship opener in Cardiff - sympathises.
"You take a win, no matter what. The way that rule was bent slightly with the quick throw-in was no different to opensides cheating at the breakdown," he said.
"The laws are there to be pushed and referees are there to make sure they're not pushed too far.
"If we'd have scored that try we'd have taken the five points. It's up to the officials to pick that up.
"We want to win and the laws are there, I suppose, as bit of a loose guide for the players to follow.
"There's no doubt we've learned a few lessons from that - if you switch off you concede points, whether it's three or five.
"Hopefully those lessons are behind us now and this is a fresh start and none of that gamesmanship will be able to take place."
The match was the first of three successive victories for Wales in what has become a thrilling and well-matched fixture - a sequence that includes the 2011 World Cup quarter-final triumph in Wellington.
Ireland are desperate to avenge three losses that have festered in their psyche and, given that since winning the 2012 Grand Slam Wales have slumped to seven consecutive defeats, they are expected to accomplish exactly that.
"When you lose to a team you double your effort to make sure you don't lose the next time you play each other," Best said.
"It hasn't got nasty - we've just been on the wrong side of the results in the last three games and we're not happy about that.
"Wales probably feel they have bit of a number on us, but we won the previous two games before losing three.
"We badly want to put the record straight. It hasn't got nasty, but we know each other so well."
Best, restored to the Ireland XV after missing the autumn with a neck injury, is thrilled that the Six Nations will start this weekend.
"It's an exciting time because it's a level playing field. Every team is on the same number of points," Best said.
"Right up until 1.30pm on Saturday it's anyone's Grand Slam to win. Come Sunday there will be only three teams who can do the Grand Slam and from that point of view it's exciting.
"No matter how many campaigns you've been involved in, this is the bit you look forward to.
"You enjoy meeting up with the lads in training, but we're all in it to play in these big games."