two part answer. In My Humble Opinion, You should avoid using a payday loan company as much as possible. The interest you pay for one of these loans is HUGE. For example if you borrow $400 for a month, you will pay more than $200 in interest. You must pay them AT LEAST $600 at the end of the month.
Having said that, if you are going to use one of them, there are any number of them that stay in line with the rules and laws surrounding their extortion. If you were to look in the Yellow Pages you will see some that have multiple sites in your area and there should be a statement in their ad somewhere that says how long they are in business, and bank affilliations. Two indicators of reliability. They may even have a BBB emblem in their ad. I would not go to one that is a single site operation, they may not be as dependable.
And no matter where you go, ask upfront about the interest you will have to pay. Get an exact figure from them, then before you actually do any business with them, go home and think about it. Can you afford to pay someone 30-40% interest . Are you going to have that money when you need to, because if you extend the loan, the interest rates usually go UP. Then you owe them even more money than before.