I just got my credit score, and it's pretty good (783), and puts me in the top tier according to their chart for typical loan rates (760-850), though not as high as I'd expect based on my financial habits. Freeficoscore.com gave a single "key factor" for my credit score:
1. You've made heavy use of your available revolving credit.
Your FICO® score evaluates your total revolving credit balances in relation to your total credit limits on those accounts. In your case, this ratio of balances to credit limits is too high.
I have no credit card debt. I use my credit cards for pretty much everything I buy (and I have four of them because of different benefits they give me on different types of purchases), and I pay them off every month. As I understand it, "revolving balance" does not refer to the monthly purchases that are paid off and on which no interest is paid, but the balance carried over and on which interest is paid. The only interest-bearing debt I currently have is my mortgage (which is not revolving credit). I've had both a HELOC and a HE Loan in the past five years, but not at the same time, both have been closed, and only the first one might be considered revolving (because it was a credit line, though I used it as a loan, and it's been paid off for about 3 years). The only time I have ever carried a balance for any extended period was during an interest-free promotional period on two of my cards. I paid each of them off before the promotions ended, which were both over a year ago. Aside from that, I think I have twice (or three times?) had bills get lost in the mail, resulting in late payment of single credit card bills. Even that hasn't happened in multiple years.
So, back to the question in the subject header... How is 0 too high of a debt ratio? Is there some way I can convince my credit card companies to perpetually owe me money so that I have a negative revolving debt ratio? 
(actually, I do that already, since all are point/cash-back cards).
If anything, I could buy the claim that my combined revolving credit limits are too high, because I've got four active cards, each of which has a limit higher than the amount I put on all four of them combined, but the ratio being described here is the ratio of debt to the credit limits, so the high cumulative credit limit actually lowers that ratio (or would, if it were nonzero). The explanation linked to with my score reinforces this point as well.
I haven't pulled a credit report very recently, and I need to do that next, but last time I did, it was accurate, so I don't have reason to believe that this is based on a major error.
Thanks for the response and the clarification. I hope it's a real FICO score; it came from a myFICO promotion.
Still, it seems odd that my revolving credit ratio would be "too high." My credit limits are, IMO, unreasonably high, and even though I use my credit cards for everything, I rarely hit 20% of my credit limit on my primary credit card, and far less than that on my other three (one of them gets used less than monthly) I expect that if I added everything up, my revolving debt ratio is probably in the 10% range. I wouldn't think 0.1 would be a high revolving debt ratio.
I'm not at all worried about my credit score (as you and I both said, it's plenty high), just curious.
@Anonymous wrote:Thanks for the response and the clarification. I hope it's a real FICO score; it came from a myFICO promotion.
Still, it seems odd that my revolving credit ratio would be "too high." My credit limits are, IMO, unreasonably high, and even though I use my credit cards for everything, I rarely hit 20% of my credit limit on my primary credit card, and far less than that on my other three (one of them gets used less than monthly) I expect that if I added everything up, my revolving debt ratio is probably in the 10% range. I wouldn't think 0.1 would be a high revolving debt ratio.
I'm not at all worried about my credit score (as you and I both said, it's plenty high), just curious.
First off, as you noted with a score of 783 you should have little to worry about. In general, the higher the score the pickier the algorithm gets; if you had a bunch of late payments and a score around 600 then your utilization of around 10% would likely not even get mentioned. I completely understand where you are coming from because my wife and I are like you heavy convenience users—we both have good jobs and carry very little cash, so we put lots of stuff on our cards which we pay in full each month. On my FICO reports the only negatives mentioned are "too many accounts carrying balances" and "revolving balance too high." I believe TU cares most about how many accounts show a balance, EQ cares most about the total dollar amount owed, and EX cares most about revolving credit used as a percentage of available credit.
If you do want to get a few more points, you could check your credit card company websites a few days before billing date and make online payments sufficient to cover the full balance plus anticipated purchases between now and billing date. However, at your FICO score range that may not be worth the bother.
I personally do think it would be preferable for the credit card companies to report the balance as of the day after due date, as that would represent the amount being carried over to the next month, but that is not how it is done.
Above a certain FICO score, further increases in the FICO score will have minimal effect on how lenders respond because other factors such as income and employment history will loom larger (and of course in the case of secured loans like houses and cars, the percentage of the downpayment).