It's a pretty simple question, but I've read a lot of conflicting information on this. From my basic understanding of credit, I know that it's good to have lots of long-standing accounts. That's why it's bad to close old credit card accounts - because it will decrease the average age of your accounts.
How is paying off an old loan different than closing an old credit card account?
I mean, I can see how decreasing debt would decrease the debt-to-income ratio and thus enable me to get a larger mortgage, but CreditKarma.com seems to indicate that debt-to-income ratio doesn't mean jack to a credit score.