Everything that has happened to an old object since it was made is recorded somewhere on it, and almost never on the side facing the camera.
Ask for the back
The underside of furniture, the reverse of a frame, the inside of a lid, the base of a vessel. Repairs, replaced parts, old labels, marks and the honest evidence of age are all there.
Then ask the direct question
"What has been repaired, replaced or restored?"
Ask it even when nothing looks wrong, because good restoration is meant to be invisible. A seller who answers specifically — "the right rear foot is a replacement, and the glass is modern" — is a seller worth bidding with.
The words to listen for
Original, repaired, restored, married, replaced. If a seller uses none of them about an old object, ask which applies. What they mean.
Measure before you fall in love
Ask for the piece measured on camera, in centimetres. Scale in a photograph is unreliable, and this is the category people most often discover that after delivery.
Ask about delivery before you bid
Heavy, fragile and awkward items are where delivery goes wrong. Ask how it will be sent, or whether collection is expected — and if it is a collection item, the arrangement is agreed before bidding, not after. How pickup works.
What protection covers
A piece with undeclared restoration, a married piece sold as original, or damage that was not described: all not-as-described, seven days from delivery.
An honest "I do not know how old this is" that you chose to bet on is not.
Questions people ask
Is a married piece worthless?
No. It is worth less than an original and it is a perfectly legitimate thing to sell — declared.
Does old damage matter if it is stable?
It affects value and it must be described. Stability is a separate point worth making.
Should I buy something I cannot identify?
If you like it at the price, yes. Just do not pay an identified price for an unidentified thing.