I know our store was part of a group about 6 months or more ago that was given permission from HQ to stop doing returns (if we knew that they were doing this couponing deal) I'm not sure if it has rolled out company wide yet or not.
This is how our store looks at it and deals with it (as far as AP goes).
Manufacturer coupons work by giving a $ value or % off an item, but in return that retail store gets that money back from the manufacturer (So think of the coupon as a currency). So it costs Target no money, it actually earns us money by whatever the % of markup is on that product. When people come and return items that they used a coupon on, they would get the full price back because that is what target received for that product, partly paid for by the manufacturer and partly paid for by the guest. The guest does come out ahead, BUT Target is not at any loss, the manufacturer is. So in a AP standpoint There is no loss to Target. The only thing we do when we see these groups roll through our store is to get a GSTL or LOD to the lane they are checking out at to make sure the coupons have not expired and they are legit.
Now for returns they will usually do a gift card look up or cc look up to do the return because they "forgot their receipt" They will get the money back on a gift card. This is where HQ has given a group of stores (maybe all by now) permission for a ETL to deny the return, they have a write up on what to say when they deny the return, but basically because target does not condone this behavior and product is for guests to use and enjoy not for your shenanigans. (in a nutshell) We (AP) at our store has also told our service desk team members this neat little trick, which 9 times out of 10 will get them to leave without having to call an ETL up there. The TM will start processing the return, then void or suspend the transaction, and tell the guest that they will have to look up the original receipt (since they never bring it with them). If the guest asks why, and we tell them they better be dang sure that its these couponers before they say this, (which is easy because its generally bags of razors, or batteries)that "there has been a lot of fraudulent returns with _______ product so we just have to see the original receipt first". So when the TM suspends the transaction it allows us to go into the system to get the original receipt ID and look up the original receipt to see if they used coupons. Usually they will bag back up their items and leave right away without another word being said.
Eventually, after they get enough gift cards from returns, they go buy some big electronics items with at least 51% cash and the remainder using gift-cards, then they will return those expensive items and receive all cash back because they paid mostly with cash. Again from AP standpoint, No Loss to Target has occurred.
If they are faked coupons, that's a whole different story because we will not receive money from those manufacturers and that would be a loss to target.
Now from a GE standpoint, I see that it is unfair to take every razor from the shelf and leave none for guests that actually want to use them. So our store will see these people and limit them. If its a big $ coupon maybe we will just say you can have 1, if its a bunch of throw away razors we say 3, and none of this breaking it into 4 transactions so they can get a cart full. Every store has a right to limit quantity of our products.
So don't get mad at AP or anyone else when we say we can't really do anything, because we can't,, they are not causing a loss to Target.
At our store we understand that if it happens its not the end of the world, Target is not really out any money, but we do try to make it as hard as possible and as slow and difficult as possible for these people that it is not worth it to come to our stores anymore.