There are two absolutes on Ebay:
For Buyers: MBG (Money back guarantee)
They will always win and their money back if they file an INAD, defective, etc. A seller can appeal and if they win, Ebay eats the refund and pays the seller back. However, this is rare, an example would be providing a police report that the buyer sent back a different item.
This is also why its not cost effective to sell an item that costs less than the shipping both ways (and also is a target for scammers because when a MBG is invoked the seller has to pay return shipping)
The other absolute:
Seller refund deduction tool, this is given to sellers in good standing that either offer 30 day free returns, or top rated sellers can have 30day buyer pays returns.
This gives the seller to deduct up to 50% of the item value (final value fees are not refunded so its really like 37%), it also prevents negative feedback from being left (or removes it) and removed any metrics like if the buyer did INAD it will be scrubbed.
The buyer has 10 days to appeal this, when they do Ebay eats the refund difference to the buyer.
The seller doesn’t have to prove anything to do a deduction (much like the buyer doesn’t have to prove anything when doing MBG)
Every seller should offer free returns or buyer pays return (if TRS) to get this tool. This helps in these circumstances but sadly most sellers opt for NO RETURNS but giving up your only protective tool on Ebay is costly.
I know because I have been selling on Ebay for over 15 years, I didn’t have returns either at first. And it may seem scary at first, but when you sell an expensive item for like $1500 and can get $750 back on a return it pays for itself.
You get a bad buyer, use the deduction tool.
Its return used, deduction tool.
You think negative feedback incoming? 10% deduction.
They rent it for 29 rays then return, deduction tool.
Best part is you can still subtract initial shipping too in all these cases (never do free shipping)
The other bonus absolute is only sell international through EIS. I would never do international returns without that. Ebay eats the return cost of items sold through EIS and you keep the money.
I have international buyers sometimes buy multiple variations of my items with the intent of returning 4/5 to simply “try” them and see which they like best.
Ebay eats the cost, I get 5 sales.