From u/cardiacman  Tales From Retail:

So this is a story with half of it completed from one of my co-workers in our instore liquor shop.

On mobile, excuse any format issues etc.

So I get a call from a customer asking if they can return unused wine/beer/spirts from an event they had.

This call arrives after our liquor store has closed for the night, so I can't pass the customer on to them. But this sounds like it was a very large shop, upwards of a thousand dollars worth of booze.

I tell the customer that there shouldn't be any issues returning unwanted alcohol provided they had proof of purchase. They ensure me they do and that they will be in the store tomorrow. Pretty standard stuff.

Now for part two, which I did not witness. (I'll keep it in first person for simplicity)

Two customers come into the store with two trollies (shopping carts) packed full of wine bottles, beer slabs and a few vodka bottles.

They explained they're here for a return and we start scanning the returns in. Then I noticed something strange about one of the wine bottles. The aluminium cap/lid seems to have been drawn on with a permanent marker.

This raises my suspicions so I look a little closer. They have drawn over the little aluminium tabs that break off when the bottle lid is twisted off. This bottle has been opened, and been drawn on to try to conceal that fact.

I look at the customers, but they are both avoiding eye contact. I give the bottle a little twist, and it opens easily without the sound of snapping tabs. They are watching me now, guilt trying to be hidden from their faces.

With the most polite tone I can manage I say

"excuse me, but is there any possibility this bottle could have been opened?"

Their faces go red, and they admit it was opened without any further pushing. Then as I'm explaining that we can't return opened products, something else catches my attention. This wine doesn't smell. There is only a very weak hint of alcohol.

I raise the lip of the bottle to my nose and sniff. Under the weak residual alcohol smell, the cool metallic smell of our cities water.

Wordlessly, I reach across and pick up one of our tasting glasses, pour myself a glass and take a sip. Water. The bottle has not just been opened, but refilled with water.

Through a retail smile I say

"Are there any other products here that might have potentially been opened, and subsequently filled with water?"

Turns out, the only products that weren't tampered with were the beer slabs. The vodka and all of the white wines were all opened and refilled.

The customers denied doing it themselves, saying that it must have been the bar attendants they hired.

At our managers request in the name of customer service, we return their slabs, keep the other items and ask that they take greater care and responsibility next time.

We submitted a report to our loss prevention team, but sadly never heard anything about it.

TL, DR: customers try to return a couple hundred dollars worth of alcohol switched with water.

--u/cardiacman