A dark line or dot on the edge of a book’s pages can look like accidental damage. Sometimes it is a remainder mark associated with copies sold through a discounted stock channel. That possibility explains a mark’s purpose, but it does not describe the condition of the rest of the book.
The Independent Online Booksellers Association’s explanation of remainders discusses these marks and notes that some retailers use similar markings on bargain stock. Appearance alone may therefore leave the exact history uncertain.
Ask what the seller can establish
Request a clear photograph of the mark and its location. Ask whether it affects only the page edges or extends onto readable text or a cover. Keep that description separate from questions about missing pages, loose binding, damp, annotations or a damaged jacket.
For a reading copy, a disclosed edge mark may have little practical effect. For a collection with particular condition requirements, it may matter much more. There is no universal percentage discount that can be inferred from the presence of a mark alone.
A seller’s condition grade is a summary, not a substitute for the description. Read both. If a listing says “as new” and also mentions a mark, clarify what the seller means before buying rather than assuming every marketplace uses the same convention.
Leave the evidence intact
Do not sand, bleach or cut a page edge to remove a mark. Attempts to disguise it can damage the book and make a later description less honest. If you resell the copy, disclose the visible mark and any uncertainty about its origin.
Record the edition and the actual condition features you can observe. A remainder mark is one piece of a book’s commercial history; it does not prove that the text is incomplete, that the copy is unread or that the edition has a particular collectible value.