The decision not to acquire something is as important as the decision to acquire it, and considerably harder to explain.
There is always pressure, mostly internal, to find a way to say yes. The object is interesting. The price is negotiable. The seller is expecting an offer. There is a story that could be told about it.
But there are situations in which the correct answer is to leave without the piece, and recognising them is part of the work.
The first is incomplete provenance. An object whose history cannot be accounted for is an object that may carry a history you would not choose to be associated with. This is not an abstract concern. It has practical consequences at the point of resale and legal consequences in some categories. If the ownership chain cannot be reconstructed to a reasonable standard, the piece stays where it is.
The second is condition that has been obscured. A watch that has been recently polished, cleaned, and presented is a watch whose evidence has been disturbed. The same is true of a piece of furniture refinished before sale, or a painting cleaned in ways that are not disclosed. These may be innocent decisions. They may not be. In either case, the information needed to assess the piece accurately is no longer available.
The third is pressure to decide quickly. Legitimate sellers of significant objects understand that buyers need time. The seller who creates urgency is often managing information rather than inventory.
The fourth, and the hardest to articulate, is instinct. After enough years doing this work, there is a quality of wrongness that precedes analysis. The proportions are slightly off. The wear does not match the claimed use. The story shifts slightly between tellings.
Trust the instinct. Examine it later. Walk away first.