Rental application should be completed 100%. The first sign of a "sneaky" applicant is leaving gaps in the form. Be sure that all the dates are complete and you have their social security number and drivers license. Make sure you have copies of their last 2 paycheck stubs.
Review the >rental application form and make sure that all the documents that they give you match the information that they put on the form. If you do not have a rental application, you can use this one by clicking here (requires free Acrobat reader).