It's gonna be impossible to concretely discern intent from the data you could get, but it's pretty obvious there's _some_ abuse. The only question is where you draw the line on abuse and how much.
January at our store was a rush of returns of opened and used Christmas decorations because "I decided I don't want it anymore." Often times from people that had done the same thing year after year. We'll never know what those people really intended when they bought it in the fall, but you'd have to be pretty damn charitable to assume the best of intent in all the cases. Especially when it was people doing it multiple years in a row.
I assume it's some combination of degraded quality as most stuff is made in the same Asian factories and an increasingly widespread attitude that it's OK to take anything that isn't nailed down.
A couple random things - the first stack of shelves that face the front of the store are managed to give a good impression. They always keep those shelves full of pallets and try to have a lot of only a few items to give a clean look. If the warehouse has empty space they try to keep it so you can't see from the center of the store.
Add to that the people who realize what a waste of an investment that was after the holiday spree is over, you can explain it a bit more.
But of course, it's impossible to tell surely without data.
Going back to gut feelings: Does he see suspicious behavior? Weird reasons for returning?