While there are some situations where a Payday Loan is the right financial decision, it is very rare. As a rule of thumb, Payday Loans should be avoided at all costs.
Because of the incredibly high short term interests rates of a typical Payday loan, the most likely end result is a downward spiral of debt...debt...debt. This of course is the goal of the Payday Lender. They want to make as much money from you as possible.
There are alternatives to Payday loans, even if you don't have perfect credit. The ideal financial choice is a debt consolidation loan from a crowd funding institution such as Prosper.com. However, if your needs are slightly more 3rd world in nature, you might also look into Kiva.