It's only a bad idea if your intention is to incur more debt on the credit cards after paying them off with yet more borrowed money. Best thing you can do is cut up the credit cards, pay them off with whatever kind of consolidation loan you get, pay off the loan, then keep making those loan payments to yourself into an account for which you have a debit card. That way, you can still buy "like" you're used to with plastic, but you only buy what you have the cash to pay for at the time of purchase.
As for the credit, it won't hurt or help you. All you're doing is shifting debt around.
