The good news for careful givers is that in return for their tax-free status, nonprofit groups other than churches typically must make extensive public disclosures about their finances and governance. Some state authorities require useful disclosures as well.
The result is a wealth of information and analysis available to prospective donors, much of it free and easy to find online. Within minutes you can get data on an organization’s program expenses, fundraising, assets and executive compensation. Groups must even disclose whether someone has “diverted assets”—that is to say, stolen—from them.
Source: How to Vet a Charity – WSJ