What's the risk? Its non secured, non-recourse debt? The worst that could happen to you is that you get some collections phone calls and it hurts your credit.
But if you already have a house and a car, what difference does it make? Those are the main things you need credit for, other than those two things, who cares? Lets say worst case scenario, you over-leverage your credit cards and default. You spend 3 grand on a bankruptcy, the debt is gone, you just can't buy a house or a car for the next 3-5 years.
Only makes sense to pay cash for things you use right now, I have my car financed at 1.9% over 60 months, that's less than what inflation usually is. Instead of paying cash for the car, I financed it, put the rest of the money in an index fund where I expect it to earn between 5 and 10% a year. Its a no brainer.
Why are you paying off your house? My house is financed at like 5%, but I get a tax break for the interest I pay on it, so the effective rate is 3.25 % since I am in the 35% or so tax bracket. You would be much better off financially if you invested that money, its EASY to beat a 3.25% return, not to mention that the earlier you stock away your money, the greater the impact of compounding. People always talk about the "enormous amount of interest" you pay on a house over the course of a 30 year loan, but most people don't live in their houses for 30 years, most sell way before that time is up, and even if you DID stay in your house that long, interest rates are so low right now that you can get a fixed 4%
Leverage it awesome, if you know how to manage it.