Hearsay is inherently unreliable. If I lift a picture from the internet and include it in a catalog, I am vouching for the authenticity of the item when I really don't know.

I contribute images to various coin catalogs (including an occasional item for the Chip Guide), as well as Beatles records catalogs. They are always items I visually verify and can attest to.

The reliability of the catalog depends on accurate first-hand information.