Not true - @kelsmom is correct that if a law student is taking Grad PLUS loans out, then there is a credit check and a “non-approved” on that credit check can change to “approved” with a cosigner who is also subject to a successful credit check.
And let’s not conclude that all students who are not approved for GradPLUS loans is due to their poor management of money. There are many reasons a student can automatically be not approved for GradPLUS loans (outlined on the DoE website), including bankruptcy and other issues. Of course, many may draw conclusions here that reasons like bankruptcy automatically mean poor money management as well, however there can be many instances where this is also not necessarily the case. For example, a student could have incurred a huge medical debt (hundreds of thousands of dollars) as a new adult due to life threatening complications resulting from genetic conditions, possibly because he or she was under false pretense from parents or others that he or she was covered medically and then turned out not to be. The student subsequently may choose to request to discharge the debt through bankruptcy. Just pointing out that there could be reasons other than general “money mismanagement” for which individuals could not qualify for GradPLUS without a cosigner.