Ebay is a place where good value can be had, but where also banknotes can be overgraded. UNC is an important grade to get right. Below, is a 1958 Irish £1 note currently on ebay, which has been graded UNC.
It isn't UNC. I have pointed out the faults which drag the note down to the EF region. There is a big difference in value between an UNC and an EF for this note.
On ebay, especially, bidders should beware of any older Irish note graded as UNC, as generally there will always be faults in Irish notes dated earlier than the 1970s. Ebay sellers tend to be amateurs, and thus don't know how to grade properly.
An UNC note doesn't have any circulation faults at all, it should be as issued by the Issuing Authority.
EF graded as UNC