Some Americans caught in the weak job market are lining up for federal student aid, not for education that boosts their employment prospects but for the chance to take out low-cost loans, sometimes with little intention of getting a degree.

Take Ray Selent, a 30-year-old former retail clerk in Fort Lauderdale, Fla. He was unemployed in 2012 when he enrolled as a part-time student at Broward County's community college. That allowed him to borrow thousands of dollars to pay rent to his mother, cover his cellphone bill and...