There are several different types of credit. There are those who have rock-solid (Exceptional) credit scores of 800-850. Scores in the 740-799 range are deemed "very good". 670-739 Are "Good", 580-699 Fair, and pretty much anything under 580 is called poor.
Here's the thing. The truth is, these scores oftentimes DO NOT accurately predict a person's ability or willingness to pay a debt. There can be MANY Variables involved that do not necessarily even fall within the realm of (Under a person's control) and many lenders are aware of this fact. For Instance, Medical bills are a big one. Also adjustable-rate loans like mortgages that are adjusted to prime plus 2% or 3% or more, directly affect a person's debt to income ratio. With them having no control at all, (this in a big way took down our real-estate market around 2008).
All that being said, people shouldn't lose hope. (bad things happen to good people). There are ways to fix these issues. Sometimes bankruptcy is the best answer (talk to a lawyer about chapter 7 or chapter 13). Also, I can literally get some people financed to buy a car while they are still in chapter 13, and, in many cases, the day a BK discharges I can get people financed.
You can also challenge "Dispute" things on your credit. The "Fair Credit reporting act" Gives us the right to dispute anything on our credit report for any reason. The creditor sometimes responds within 30 to 45 days at which time the debt will be reinstated on your credit, but if they don't, the debt is removed.
One Great way to rebuild credit, is with a car loan through an accredited lender. (I have serveral). I get car deals done for people all the time who are suffering from credit issues. If you have a need, I can help! shoot me a message or contact me through my website.