Frame dents. Plastics that are rashed. Brake and tire wear. Fluid levels. Oil change records. Bottoms of footpegs and grips for indications of having been down.
These aren't so much show-stoppers as they are leverage for a lower price.
IMO, you shouldn't be paying extra for aftermarket mods unless you were certain you'd do the exact same modification.
For price ranges on the bike, refer to NADA or Kelley's Blue Book (both avail free online).
Dragging knee is for the track, and dragging tail is for the lot. --Kane Friesen
When you're in a car, you're watching a movie; when you're on a bike, you're in the movie. --Robert Pirsig
Identity theft is not Fun