McCarthy is bemused that ITV have chosen to show tonight's meeting live after the lacklustre and goalless 90 minutes at St Andrew's when chances were at a premium.
But he believes the return will be a "barnstorming" encounter even though both sides will again make several changes from their league league line-ups, saying: "Those who watched the first game probably won't come back. That's 14,000 not coming already."
He added: "Why the hell it is on TV after the first game? People say the first game was dreadful. It wasn't as good as that. It was just a damp and dreary old day coming on the back of Christmas. It felt like a damp squib from the start.
"I guess everyone is hoping for a better game. I guess lightning can't strike twice. Let's hope not. It will be a barnstorming cup-tie. Our games generally are exciting. We score and concede goals and it will be different to the first game.
"We both want to get through and we both want to get through in 90 minutes. None of us want to play two hours of dreary, drab football. We are playing 4-4-2, we are going for it."
McCarthy will rest nine-goal leading scorer Steven Fletcher and injury deprives him of former Blues defender Roger Johnson, who has an ankle problem. But he is adamant Wolves want to progress in the competition as they take a break from their battle for Barclays Premier League survival.
McCarthy said: "We still want to do well in the cup. It does matter. There will be a much changed team in the replay but there will be a strong team. For example, Kevin Doyle and Sylvan Ebanks-Blake will start upfront and a lot of teams would be thrilled to have those two upfront."
Birmingham, who will also make changes, have rejected a bid from West Brom for defender Liam Ridgewell.
The Baggies enquired last summer about Ridgewell who submitted a transfer request towards the end of the last transfer window. He is one of the few survivors still at the club from the side which won the Carling Cup 11 months ago.