Actually TSteven is right, the biggest risk is/was Title IX related. Little sisters threatened fraternities' single sex status.
Some little sister programs weren't run honorably, but some were more organized than the fraternities OR some of the sororities. It varied greatly from group to group, school to school - same as NPC sororities and NIC fraternities. When all little sisters are characterized as sluts or servants it pisses me off no end, as some of my best friends in college were fraternity little sisters. It was usually sorority women who spread those rumors - I'm guessing because they were jealous at the proximity the little sisters enjoyed.