Almost every unhappy outcome in this category was avoidable with one question asked thirty seconds earlier.
The questions
"Can you measure height, width and depth on camera?" Then measure your own space, your doorway and your stairs. Photographs are unreliable about furniture scale in both directions. Non-answer: "It's a standard size."
"How is it getting to me?" Courier, seller delivery, or collection. If collection, the terms are agreed before you bid and there is a collect-by date. A heavy item you cannot collect is not a bargain. How pickup works.
"Is it solid wood, veneer, laminate or engineered board?" It changes the value, how it can be repaired, and how it survives moving.
"Can you work the drawers and doors?" On camera. They tell you more about a piece than the finish does.
"Any wobble, woodworm, water marks or old repairs?" Ask for the underside and the back.
"Has it been refinished?" On anything old, that usually subtracts.
What protection covers
Measurements materially wrong, undisclosed damage, veneer sold as solid, a different item: seven days from delivery. An item that does not fit a room you did not measure is not.
Questions people ask
Can I ask for it measured mid-show?
Yes, and good sellers expect it.
Will it be dismantled?
Ask, and ask whether fixings will be bagged and labelled.
Is collection-only a bad sign?
No — for anything large it is the honest answer.