Things whose condition cannot be settled by a photograph. That is the whole rule, and it cuts across every category.
If two examples of a thing can look identical in a picture and be worth very different amounts in the hand, live selling earns its hour. If they cannot, it does not.
What that means in practice
Second-hand anything. Wear, repairs, fading, fit — none of it photographs honestly, and all of it is what the buyer is actually deciding about.
Collectibles with a grade. Cards, comics, coins. A tilt to the light shows what a scan cannot. How to judge an item through a camera
Handmade work. Every piece differs, and the maker explaining it is most of why somebody wants that one.
Textiles. Drape, weight, the way zari catches light. A saree held up and moved is a different object from a saree photographed flat.
Jewellery. Colour and sparkle are notoriously unphotographable.
Estate and clearance stock. Mixed, uncertain, and the uncertainty is the appeal.
What does not
New, sealed, uniform goods. There is nothing to show and no uncertainty to resolve. A buyer who knows the model will search for the cheapest one, and an hour of your talking does not change that.
Anything with a published price everyone can check. The auction either matches it or loses.
Very cheap items on their own. The delivery dominates, and the room will not get excited about something worth ₹200. Bundle them. How to list a bundle
The second property that matters
That you can say something true and interesting about it. A show is an hour of talking, and stock you cannot talk about is the real reason some shows die — not the items, the silence.
Which is why sellers do best with things they genuinely know. Where do sellers find stock?
What a good lineup looks like
A mix of price levels. Something cheap early to get people bidding, the good pieces in the middle when the room is fullest.
Twelve items shown properly rather than twenty rushed. How many items should a show have?
Not everything at once. Unsold items cost nothing to run again, so holding some back for the next show is free. What happens to items that do not sell?
How to find out for your own stock
Run the same kind of item in a show and as a plain listing, and compare. Three or four comparisons tell you more than any general advice, including this page. How to find your store's numbers
More: is selling live actually worth the effort, why some things sell better live, how to price for auction.