Kelley Blue Book condition definitions 
Excellent: Looks new and is in excellent mechanic condition. 3 percent of trade-ins fall into this category.
Very good: Has minor cosmetic defects and is in excellent mechanical condition. 23 percent of trade-ins fall into this category.
Good: Has some repairable cosmetic defects and is free of major mechanical problems. 54 percent of trade-ins fall into this category. 
Fair: Has some cosmetic defects that require repairing and/or replacing. 18 percent of trade-ins fall into this category.