Yea they do, all items I return to my local outlet are sold for retail. The only time they immediately discount is if it's something that's already being sold by nike at a discount.
I agree that nike outlets sometimes sell for retail but I don't agree that they are only being sold at a discount if nike has already sold it at a discount. The price that comes up is pretty hit or miss. I've had stuff come up as discounted within a couple of days from release and others come up as full price. I've also seen managers hold items until nike updates the price in the system because it doesn't have an outlet price yet.
I haven't had a lot of experiences returning to outlets, the only pairs I returned that were immediately discounted were weatherman and tampon foams.
All other shoes were thrown out there for retail, I'd imagine that if an outlet discounted everything returned people would take advantage of that to death.
You could literally return everything you bought on ndc and repurchase it at discount.