Biarritz reached their first showpiece European occasion after scoring just one try in disposing of knockout-stage opponents Sale Sharks and Bath, relying instead on scrum-half Dimitri Yachvili's goalkicking accuracy for points.
But fly-half O'Gara, who plays in his third European Cup final this weekend, has challenged the critics' outlook.
"I think Biarritz are a hell of a side," he said. "They have quality players throughout their team.
"I don't buy into this notion that they are a dour side because of the way they played in the quarter-final against Sale, or semi-final against Bath.
"Those games are about winning and getting to the next stage, and Biarritz saw off two good teams with the minimum of fuss.
"They showed in those games they can mix it with the best, and then they have players in their back division such as Damien Traille, Nicolas Brusque and Philippe Bidabe, who are very good ball-carriers and runners."
Munster, though, will arrive in the Welsh capital as favourites to finally land a trophy they have coveted for so long.
The pain has not gone away following the defeat to Northampton at Twickenham six years ago and the narrow loss against Leicester at the Millennium Stadium two seasons later, while Munster's often heroic European Cup history also shows three semi-final and two quarter-final exits.
Now could be the time for O'Gara and company to deliver on the back of a thumping semi-final victory over Leinster in Dublin four weeks ago and join previous tournament winners Toulouse, Brive, Bath, Ulster, Northampton, Leicester and Wasps.
Both previous European Cup meetings between the sides were quarter-final encounters, with Munster toppling Biarritz 38-29 in 2001 and the French club avenging that result through a 19-10 success in San Sebastian last season.
But Biarritz, bristling with Test-class talent throughout their squad, have enough quality to pile fresh misery on a team desperate for European Cup success.