If a bad credit rating keeps you from spending more money and getting further into debt (by way of preventing you from getting more credit cards and/or loans), then it can be a good thing in a very limited way.
Unfortunately there are many downsides to this and you’re much better off reining in your spending [...]

If your credit is non-existent or damaged enough that you can’t get an unsecured card even with a very low credit limit, then secured or prepaid credit cards may be your path to rebuilding credit.
With these cards, you usually make a deposit (e.g. in a savings account with the issuing bank) which will be used [...]

For most people with bad credit, unsecured credit cards are going to be harder to get than a secured or prepaid credit card, but unsecured cards may still be available.
Try http://creditfederal.com or http://www.orchardbank.com for a couple of possibilities.
You can use these credit cards to rebuild credit which has been damaged in the past, and they [...]