this is crap. luckily i only have one card that has a balance on it. i just put some clothes on my Sears card but i plan to pay that one off. i went through that whole credit card debt stuff a few years ago and it really sucks. most of the time i was just paying the interest on one of the cards and it came down to me selling my car and buying a POS just to pay off that credit card.
If you close them off, you tell the company that you want it stated that the account is being closed by YOU. This will keep it from hurting your score, even though it wouldn't lower your score by much or for long anyway.
If you mean it hurts your credit score by paying the card off each month, it has never hurt mine. Mine is in the 800s.