Most disappointments here are not about condition. They are about which edition, and which volumes.
The questions
"Which volumes, by number?" Not "most of the set". The actual numbers, read out or shown with the spines facing the camera. Gaps are expensive to fill. Non-answer: "near complete".
"Can you show the publication page?" Publisher, imprint, language and printing, all in one frame.
"Is this an official licensed release?" And where did they get it. Unofficial printings exist in this category; describing one honestly is a sale, describing it as official is not. Counterfeits policy.
"Standard, deluxe, omnibus or collector's?" Different items at different prices. An omnibus is not the singles.
"What are the spines like?" Creasing, cracking and whether a book has been read flat.
"Are the dust jackets present?" Where the edition had them, their absence is a real deduction.
What protection covers
A different edition than described, missing volumes, undisclosed damage, or an unofficial printing sold as official: seven days from delivery. The last is also worth reporting.
Questions people ask
Is a reading copy worth bidding on?
Yes, at reading-copy prices.
Does yellowing matter?
To value, yes. Ask for the page edges shown.
What about figures?
Ask for every face of the box and whether it has been displayed in sunlight.