What a feed audit actually finds

1. Active disapprovals — how much of the catalogue is not in the auction at all.
2. Products never served — eligible but invisible, usually a data problem.
3. Identifier coverage — GTIN, brand, MPN.
4. Title quality against actual converting search terms.
5. Variant grouping — whether you compete with yourself.
6. Price and availability accuracy against live pages.
7. Image compliance and whether the main image reads at thumbnail size.
8. Segmentation — whether custom labels exist to let budget follow margin.

The interesting output is usually item 2: the share of the catalogue that has never had an impression. Feed optimisation in detail.