TLDR: Low interest debt that provides long term financial gain is good. Mortgage for primary residence is almost always considered good. Loans to invest into your home that increase its value and make it more reliable/long standing is good. Low interest debt to buy assets for your business is good. Reasonable loans for college is considered good.
Car loans are a bit harder because they lose value as time goes on. But a small loan with good interest is usually considered fine for a car. Buying a brand new car with a loan will almost always be bad, since you're paying interest to use a depreciating asset. But basically a car loan is always bad if it ever goes upside down, meaning you owe more on the loan than the car is worth. New cars that happens almost instantly.