Ask early. On a standard lot a bid in the last ten seconds puts the clock back to ten, so there is room — but on a sudden-death lot the clock never moves, and a question at five seconds is a question asked too late.
Better still, ask on the listing before the show. Questions there are public: one person asks, and everybody who arrives later reads the answer. How bidding works.
The questions
"What size, exactly as printed inside?" Not the size you think it is — the one on the tag. Sizes differ across regions and the tag settles it. Non-answer: "It's a nine." Good answer: the tag, on camera.
"Can I see the soles?" Wear shows there first. A seller who has done this before shows them unasked. Non-answer: another photo of the top.
"Any yellowing, and can you show it against something white?" Midsole yellowing is permanent and it is invisible under warm light.
"Deadstock, VNDS, or worn — and what does the box look like?" For a deadstock pair the box is part of what is being sold. Condition words.
The question for anything branded
"Where did you get them?"
Nobody authenticates a pair over a video call. What a good seller gives you is a history and what they can show; what a weak one gives you is confidence. Price the difference. Buying sneakers.
What protection covers
Undisclosed wear, a different pair than shown, a size that is not the size described — all not as described, seven days from delivery. A pair you decided to trust on an unanswered question is not.
Questions people ask
Is it rude to ask mid-show?
No. Sellers expect it, and a good one builds time for it.
What if they do not answer?
Bid as though you had not asked, or do not bid.
Can I ask before the show?
Yes, on the listing, and that is the best time.