It depends on the make of the bike and location of nick, chip or scrape.

In my opinion battle wounds are OK....a chip from the front caliper hitting the down tube, chips from pumps etc. If there's a big chip or scratch in area that's clearly visible, say across the down tube decal then yes, it reduce the price. And dents always reduce the price.

$800 FMV is relative. If your asking how much an otherwise undamaged bike take at it's relative. Randy's Legnano is probably worth more as its versus being reapinted but it's certainly worth less than if it had no issues.

What make of bike are talking about? Nobody cares if a Chevy or Ford (Trek Giant) is scratched but everyone cares if a Ferrari or Lambo (Colnago Pinarello) is scratched.