Can't make the electricity bill this month? You don't want the power shut off, so a payday loan is a reasonable option in this case. Need to see a doctor but don't have insurance? Your health is too important to risk delaying.
What you don't want to be doing is getting into the habit of continually borrowing payday loans on a monthly or biweekly basis. You're better off getting a larger loan from a bank at a lower rate of interest, or taking a cash advance from a credit card company.
The key to keeping loans under control is to limit their size and frequency. Sometimes when you borrow too much you aren't left with enough money after repaying the loan which encourages you to borrow again.
One way that we help avoid that is by limiting loans to no more than 25% of your gross monthly income. If you're paid biweekly that should leave you plenty of money after repaying the loan to avoid taking out another one.