USDA Licensing does require the breeder to have a MINIMUM of 4 breeding female animals (not just gliders) before they can even apply for a license.
Having a USDA License does not define the quality of the breeder's care of the gliders. There are many licensed breeders that have more gliders (or other animals) than they can possibly give individualized attention to when it comes to handling joeys to get them comfortable with people. The USDA Inspections are more about breeders meeting minimum standards. Much of the inspection deals with record keeping. The requirements for cage size, which is that the animal can stand up and turn around, is no where near the large size most of us fee is minimum for sugar gliders.
Many breeders we would consider Mill Breeders are USDA Licensed.
Pocket Pets is a USDA Licensed BROKER - they do not breed gliders, they buy them in large groups from mill breeders and re-sell them. Their inspection reports do not have any violations because they keep all their records according to USDA requirements and they have NO ANIMALS at their licensed location.
That said to put things in perspective - there are many small sugar glider breeders that breed only 2 or 3 pairs of gliders that are carefully selected for their compatible lineage to ensure there is no inbreeding. These breeders often consider their gliders PETS first, money makers second - and most do not make much on their sale of gliders.
Here is a list of Breeders by state that might help you locate breeders to purchase gliders from.
http://www.sugargliderhelp.com/links/pages/Sugar_Glider_Breeder_Database/United_States/index.html
I believe Georgia is the only state that requires owners to purchase gliders ONLY FROM USDA LICENSES BREEDER or BROKER.