As advised, you are going against Ebay's cosmetics policy by selling used perfumes. There is no 'used' category for perfumes - it is either 'new' or 'new other'.
The Ebay definition of 'new (other)' is 'A new, unused item with absolutely no signs of wear.' Anybody you have sold a partly used fragrance to can open and win an 'item not as described' case.
https://www.ebay.co.uk/help/policies/prohibited-restricted-items/cosmetics-perfume-policy?id=4290&st...
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)