Tenant screening services come in many "shapes" and "flavors". Landlords can call in the request or find an online service. Many services offer much more than just a credit report. The basic service would include a credit report and maybe an eviction report.
The most complete tenant background check would include the credit report, eviction report, possibly a criminal report, and would verify the applicants current job and their residency history. Spending a little extra on tenant screening services is well worth the minimal extra cost.
It's simply cheap insurance. When you think of what can happen with a bad tenant, you know that you want to do everything in your power to avoid getting that "nightmare" scenario. And it's not always just financial. Many landlords feel a responsibility to their community to try and rent to the best people possible. Often their rental property is their old home, and the neighbors are their old neighbors -- or even their family! So it makes sense to do extensive background checking to make sure you have reputable tenant coming into your property.
And it's so inexpensive these days to do your due diligence. There really isn't any reason not to do what you can to reduce your risk. The big property management firms have this down to a science. They know that the secret to making a profit in this game is to do everything you can to get the right people in your property.