Third Party Originations

Do many of you work with TPO's?  I have found that the majority of them do not qualify their clients properly.  They either use income that is not there or overlook the credit.  When you let them know that the loan will not be approved, they get extremely upset.  I feel there should be more classes on how to qualify a borrower so you don't run in to that problem, as there is a lot of work put into a file and then to find out it does't qualify is quite disturbing.  Any suggestions on how to approach the TPO's and be very gracious about it?