Some people say that if you borrow money to buy an asset that makes you more money than the monthly debt payment it's a good debt. Most of the people who say that are lenders or their brokers. I say the only good debt is one that's paid off!
Before the housing meltdown I used to believe the idea that some debts could be considered good debts, such as mortgages on investment property. Unfortunately investment properties were effected just like any other residential properties when home values began to decline. when the decline got so bad that I was upside down on my properties it became painfully apparent that my good debt had gone bad - very bad. My advice would be to view all debts as a liability and be very wary. No one can really predict the future and nothing guarantees a debt won't go bad, no matter how good it looks at first.
The "Good Book" says that: "Just as the rich rule over the poor, the borrower is servant to the lender." If you want a prosperous and financially free life, you need to avoid borrowing your way into financial slavery. I'm always amazed how we refuse to listen to what God says about debt, then wonder why our finances have become a living hell.