Do i have to give them a refund.
In theory no, not if you described it properly.
In practice all our buyer has to do is to complain to eBay that it is not as described in some way. EBay never sees the item and takes the buyer's word unless the seller can prove otherwise.
As has been said, the danger is that some buyers will "make sure" there is a fault to justify returning things.
In all but name eBay has become sale or return. It would be more honest and prevent buyers from telling lies if eBay said so.