LeBron James scored a game-high 30 points in the fixture to send Miami into a 3-0 lead, with the Heat now having won 19 consecutive games against the Bobcats.
"The guys were locked in and we certainly saw carry-over, not only the activity level, but the focus and the details," Spoelstra told reporters after the game.
"It was a professional win. It was too easy for them in the first quarter. Then that changed. Everybody was upset about it and their disposition changed.
"The guys just fed off their energy and made it change on the scoreboard."
The teams play their Game Four fixture on Monday in Charlotte.